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Wind power gears will be excessively worn due to lubrication failure during operation. Herein, the tribological properties of rubbing pairs are improved by filling solid lubricants into surface texture. In texture design, three types of topological textures (Circle (C), Hexagon (H) and Circle/Hexagon (CH)) were obtained by cell topology optimization, and then three cases with 20%, 30%, and 40% density were designed for each texture. Next, SnAgCu and TiC were deposited in texture of AISI 4140 steel (AS) to obtain 9 kinds of self-lubricating surfaces. Among them, AS with 30% CH density (AS-CH30) exhibits excellent mechanical and tribological properties. Compared with AS-C and AS-H, the maximum equivalent stress of AS-CH was decreased by 10.86% and 5.37%, respectively. Friction coefficient and wear rate of AS-CH30 were 79.68% and 78% lower than those of AS. The excellent tribological performances of AS-CH30 can be attributed to the synergistic effect of topological surface and solid lubricants. Topological surface can not only reduce fluctuation of equivalent stress, but also promote the stored lubricants to be easily transferred at the contact interface to form a 200 nm lubricating film containing solid lubricants (mainly), oxides and wear debris. [ABSTRACT FROM AUTHOR]

Inspired by the scales on the surface of crucian carp, the biomimetic fan-shaped textures were designed and prepared on the TC4 contact surface and filled with solid lubricant SnAgCu-Nb2C (SACN). The coupling effects of fan-shaped textures and solid lubricants on the tribological properties of TC4 under variable frequency conditions were investigated. The results indicated that the fan-shaped textures could promote the precipitation of lubricants and provide sufficient lubricants for the worn surface, forming a uniform lubricating film on the worn surface, thus improving the tribological properties. In addition, at the low-frequency stage, the coupling of lubricants and textures had strong adaptability to frequency changes. [ABSTRACT FROM AUTHOR]

Ovarian metastasis is one of the major causes of treatment failure in patients with gastric cancer (GC). However, the genomic characteristics of ovarian metastasis in GC remain poorly understood. In this study, we enroll 74 GC patients with ovarian metastasis, with 64 having matched primary and metastatic samples. Here, we show a characterization of the mutation landscape of this disease, alongside an investigation into the molecular heterogeneity and pathway mutation enrichments between synchronous and metachronous metastasis. We classify patients into distinct clonal evolution patterns based on the distribution of mutations in paired samples. Notably, the parallel evolution group exhibits the most favorable prognosis. Additionally, by analyzing the differential response to chemotherapy, we identify potential biomarkers, including SALL4, CCDC105, and CLDN18, for predicting the efficacy of paclitaxel treatment. Furthermore, we validate that CLDN18 fusion mutations improve tumor response to paclitaxel treatment in GC with ovarian metastasis in vitro and vivo. 'Gastric cancer metastasis to the ovary is difficult to treat and is not fully understood. Here, the authors characterized mutations in a cohort of matched primary and metastatic disease, and found mutations, including in CLDN18, could predict treatment response to paclitaxel. [ABSTRACT FROM AUTHOR]

Precise and timely prediction of crop yields is crucial for food security and the development of agricultural policies. However, crop yield is influenced by multiple factors within complex growth environments. Previous research has paid relatively little attention to the interference of environmental factors and drought on the growth of winter wheat. Therefore, there is an urgent need for more effective methods to explore the inherent relationship between these factors and crop yield, making precise yield prediction increasingly important. This study was based on four type of indicators including meteorological, crop growth status, environmental, and drought index, from October 2003 to June 2019 in Henan Province as the basic data for predicting winter wheat yield. Using the sparrow search algorithm combined with random forest (SSA-RF) under different input indicators, accuracy of winter wheat yield estimation was calculated. The estimation accuracy of SSA-RF was compared with partial least squares regression (PLSR), extreme gradient boosting (XG-Boost), and random forest (RF) models. Finally, the determined optimal yield estimation method was used to predict winter wheat yield in three typical years. Following are the findings: 1) the SSA-RF demonstrates superior performance in estimating winter wheat yield compared to other algorithms. The best yield estimation method is achieved by four types indicators' composition with SSA-RF) (R2 = 0.805, RRMSE = 9.9%. 2) Crops growth status and environmental indicators play significant roles in wheat yield estimation, accounting for 46% and 22% of the yield importance among all indicators, respectively. 3) Selecting indicators from October to April of the following year yielded the highest accuracy in winter wheat yield estimation, with an R2 of 0.826 and an RAISE of 9.0%. Yield estimates can be completed two months before the winter wheat harvest in June. 4) The predicted performance will be slightly affected by severe drought. Compared with severe drought year (2011) (R2 = 0.680) and normal year (2017) (R2 = 0.790), the SSA-RF model has higher prediction accuracy for wet year (2018) (R2 = 0.820). This study could provide an innovative approach for remote sensing estimation of winter wheat yield, yield. [ABSTRACT FROM AUTHOR]

Inspired by the ability of biological structures to resist water pressure and flow resistance, this regulating mechanism was applied on the hydraulic cylinder. Bionic rhombic textures were combined with SnAgCu-Ti2C3Tx (ST) to improve the tribological properties of 42CrMo. After optimizing the texture parameters, the friction tests were performed on optimal experimental parameters-ST, predicted optimal structural parameters-ST and control experimental groups under dry/oil lubrication. Herein the optimized structural parameters were more conducive to the spreading of solid lubricants. The lubricating film was firmly bonded with substrate. The synergistic effect of optimized structural parameters, ST and oil lubrication can significantly improve the tribological properties of 42CrMo. [ABSTRACT FROM AUTHOR]

Inspired by the fan-shaped scale and mechanism of mucus secretion of crucian carp surface, the bionic scale textures were designed and combined with Sn-Ag-Cu-Nb2C to fabricate TC4-based self-lubricating composites (TTSACN). The optimal textured parameters (radius = 710 μm, width = 300 μm, depth = 390 μm) were obtained by response surface methodology (RSM). The friction and wear behaviors of TTSACN under dry friction conditions were studied. The experimental results showed that the optimal bionic texture could capture wear debris and promote the restoration and migration of lubricants on the worn surface, improving the formation quality of lubricating film. Compared with TC4, the friction coefficient and wear loss of TTSACN with optimal bionic texture were reduced by 23.03% and 96%, respectively. [ABSTRACT FROM AUTHOR]

Neurotrophic tyrosine kinase (NTRK) fusions involving NTRK1, NTRK2, and NTRK3 were found in a broad range of solid tumors as driver gene variants. However, the prevalence of NTRK fusions in Chinese solid tumor patients is rarely reported. Based on the next-generation sequencing data from 10,194 Chinese solid tumor patients, we identified approximately 0.4% (40/10,194) of Chinese solid tumor patients with NTRK fusion. NTRK fusions were most frequently detected in soft tissue sarcoma (3.0%), especially in the fibrosarcoma subtype (12.7%). A total of 29 NTRK fusion patterns were identified, of which 11 were rarely reported. NTRK fusion mostly co-occurred with TP53 (38%), CDKN2A (23%), and ACVR2A (18%) and rarely with NTRK amplification (5.0%) and single nucleotide variants (2.5%). DNA-based NTRK fusion sequencing exhibited a higher detection rate than pan-TRK immunohistochemistry (100% vs. 87.5%). Two patients with NTRK fusions showed clinical responses to larotrectinib, supporting the effective response of NTRK fusion patients to TRK inhibitors. [ABSTRACT FROM AUTHOR]

Due to the excellent properties of titanium alloys, they are widely used in various fields. However, the poor tribological performance limits the further development of titanium alloys. In this paper, TC4 with microporous channels was manufactured by laser additive manufacturing technology. On this basis, TC4-Sn-Ag-Cu (TSAC) and TC4-Sn-Ag-Cu-Nb2C (TSACN) self-lubricating materials were prepared. The friction and wear tests were carried out under dry friction conditions, and tribological behaviors and friction-induced noise were analyzed. The results show that TSACN self-lubricating composite has outstanding tribological properties and noise suppression performance. Compared with TC4, the friction coefficient and equivalent sound pressure level of TSACN are reduced by 20.1 and 6.7%, respectively. The excellent tribological properties are mainly attributed to the synergistic effect of microporous channel and Sn-Ag-Cu-Nb2C. Microporous channel can promote the diffusing of lubricants and accelerate the formation rate of lubricating film; Nb2C can enhance soft metal lubricant Sn-Ag-Cu to make the lubricating film more dense. The lubricating film can repair wear pits, furrows and other defects on the worn surface and avoid the direct contact between the counterpart ball and the sample, thereby improving the tribological properties of TC4 and reducing the friction-induced vibration and noise. [ABSTRACT FROM AUTHOR]

Inspired by rhombic textures on shark skin surface, this paper designs bionic micro-textures filled by solid lubricants SnAgCu and Ti3C2TX to improve the tribological properties of 42CrMo steel. Compared with 42CrMo steel, the average friction coefficient and wear depth of 42CrMo-SnAgCu-Ti3C2TX with bionic micro-textures at 25 N were separately decreased by 41.52 and 79.07%, and decreased by 50.77 and 80% at 35 N, respectively. Two-dimensional material Ti3C2TX can be well combined with SnAgCu to promote the formation of a smooth and continuous lubricating film on the worn surface, which plays an excellent antifriction and wear resistance role under the specific working conditions. [ABSTRACT FROM AUTHOR]

As the primary source of carbon dioxide fixation, vegetation is critical to the carbon sink process. In this paper, the Net Primary Productivity (NPP) and the Gross Primary Productivity (GPP) were simulated using the Carnegie-Ames-Stanford Approach (CASA) model and the Vegetation Photosynthesis Model (VPM), respectively, and then the Potential Gross Primary Productivity (PGPP) and the GPP affected by human activities (AGPP) were simulated by combining Potential Net Primary Productivity (PNPP), and then the impact of climate change and human activities on GPP was assessed in the Heihe River Basin (HRB). The results showed that the GPP of grassland and Bare or Sparse Vegetation (BSV) exhibited a fluctuation rise, with increases of 0.709 gCm−2 a−1 and 0.115 gCm−2 a−1, respectively, whereas the GPP of cropland showed a fluctuation reduction, with a decline rate of −0.465 gCm−2 a−1. Climate change and human activity are both positive for vegetation growth, and human activity being the primary factor influencing GPP change. Human-dominated vegetation restoration accounted for 56.1% of the overall restoration area, with grassland GPP being the most visible response to human activities. The GPP changes in crop and grassland had a positive correlation with precipitation but a negative correlation with temperature among climate change factors, whereas the GPP changes in BSV had a negative correlation with both precipitation and temperature. Quantitative analyses of climate change and human activities' dynamic contributions to vegetation can give scientific and theoretical insight for dealing with global climate change. [ABSTRACT FROM AUTHOR]

To improve the tribo-performance of molybdenum disulphide lithium grease (MDLG), the tribological behaviors of 42CrMo under grease lubrication with Ti3C2 as an additive were systematically studied. The results show that when the concentration of MXenes-Ti3C2 in MDLG is 2 wt.%, the friction coefficient and wear volume loss could be respectively reduced by a maximum of 69 and 98%. This is mainly attributed to the graphitization of MXenes-Ti3C2 induced by the friction. It retards the breakage of soap fibers and in turn significantly improves the tribological performance of MDLG under the low speed and high load conditions. In order to predict better working conditions for obtaining the excellent tribological behavior, the experimental results were used to develop a Genetic Algorithm-Artificial Neural Network (GA-ANN) model. Under the predicted working conditions, the estimated friction coefficient (R2 = 0.993) and wear volume loss (R2 = 0.934) were close to the experimental results. This study could provide the support for the application of MXenes-Ti3C2 as an additive in the lubrication grease. [ABSTRACT FROM AUTHOR]

To improve the tribological performance of CSS-42L bearing steel, smooth surfaces (SSs), groove-textured surfaces (GSs), GSs with Sn-Ag-Cu (GSs-SAC), and GSs with Sn-Ag-Cu-Ti3C2 (GSs-SACT) were prepared on CSS-42L. In addition, experimental studies were conducted on tribological properties. The obtained results indicated that GSs-SACT exhibited the best anti-friction and noise reduction performances. These remarkable tribological performances were attributed to the synergistic effects of grooves, Sn-Ag-Cu, and MXene-Ti3C2. The inconsistent rules of frictional forces were improved by the grooves and SACT, which inhibit the friction-induced noise. The micro-nano size-effects of MXene-Ti3C2 enhanced the repairing effect and anti-friction property of composite lubricants, which improved the profile characteristics of GSs-SACT. [ABSTRACT FROM AUTHOR]

In order to meet the stricter friction performance requirements of large machinery in the application field of slewing bearing, 42CrMo steel is taken as the research object. Through the preparation of smooth surface, groove textured surfaces with different densities and deposited Sn-Ag-Cu (SAC) solid lubricants, the tribological properties of samples with different surface treatments were, respectively, studied under the grease lubrication. The results show that the design of grooves can effectively alleviate the secondary damage of wear debris on the sample surfaces. Under the grease lubrication, the sample with SAC deposited on the surface has the smallest friction coefficient and deformation, which is mainly attributed to the synergistic effect among grooves, solid lubricants, and grease. [ABSTRACT FROM AUTHOR]

In order to further understand the role of MXene-Ti3C2 in oil–solid synergistic lubrication, three kinds of microporous channel composites, M50, M50-Sn-Ag-Cu and M50-Sn-Ag-Cu-Ti3C2, were designed and prepared in this study. Tribological behaviors under different environmental conditions of oil lubrication and dry friction were analyzed. The results show that M50-Sn-Ag-Cu-Ti3C2 exhibits excellent tribological properties under oil lubrication. Mxene-Ti3C2 enhances the strength of solid lubricant film, so that the oil film can give full play to the antifriction and wear resistance of solid lubricant film. The synergistic effect of lubricating oil, solid lubricants and bionic curved microchannel reduces the friction coefficient and wear rate. The vibration acceleration along the reciprocating direction is also reduced. [ABSTRACT FROM AUTHOR]

A study on the value accounting of forest carbon sink services can promote the rapid development of the carbon sink market and help better understand the impact of forest carbon sinks on climate change and economic development. However, few studies have evaluated the value of China's current forest carbon sink services. Based on research on carbon peak and carbon neutrality, according to the characteristics of China's forest ecosystems and forest resource inventory data, the stock volume method was used to measure the amount and value of forest carbon sinks in China in 2009–2013 and 2014–2018. The results showed that: (1) the physical amount of forest carbon aggregates in China increased from 2009 to 2013 and from 2014 to 2018. The carbon storage of natural and plantation forests both showed an upward trend. Among them, the growth rate of the carbon storage of plantation forests was higher than that of natural forests. (2) The state, adjoint, and coupling equations of forest carbon sinks were employed to ascertain the best price for China's forest carbon sinks in 2020. The results showed that the price of China's forest carbon sinks was slightly higher than the internationally accepted carbon sink price, reflecting that the changes in the value of China's forest carbon sinks and international carbon sinks were roughly the same. (3) We obtained an appropriate accounting model for China's forest carbon sinks. (4) The value of China's forest carbon sinks increased from 2009 to 2013 and from 2014 to 2018. Although the price of carbon sinks has declined, the overall forest resource stock has increased, especially in plantation forests. The increase in the value of carbon sinks was as high as 24.7%, resulting in an overall increase in the value of forest carbon sinks, which was also in line with the physical amount of forest carbon sinks. The measurement conclusions were consistent. Several key points to note based on these findings are as follows: (1) China's current forest carbon sink transactions are all project-level certified emission reduction transactions, and diversified non-market means should be constructed to comprehensively promote carbon sink transactions. (2) China's current carbon sink transactions are mainly clean development mechanism projects, with few transactions between enterprises, and the carbon trading market situation is not optimistic. (3) The key to effective forest carbon sequestration trading is the accurate accounting of forest carbon storage and carbon sequestration value. Thus, it is of great significance to establish a forest carbon sequestration measurement method that is economical, simple, and accurate. (4) The physical amount and value of carbon sequestration of China's forest resources are rising, and the contribution rate is increasing year by year. However, there is still a gap in per capita forest area and storage compared with those in other countries worldwide. Thus, China must be vigilant in times of peace and further strengthen the protection and construction of forest resources. [ABSTRACT FROM AUTHOR]

M50 steel is one of the most widely used high-performance bearing steels, and the tribological properties are related to its service life. In this paper, the dry sliding tribological tests of M50, M50-Sn-Ag-Cu and M50-Sn-Ag-Cu-Ti3C2 against Si3N4 ceramic balls under different loads were carried out. Through the analysis of worn surface and cross section of wear scar, as well as characteristics of friction signal, the causes of frictional noise are discussed, and the influence of Ti3C2 on the frictional noise is revealed. The results show that the addition of Ti3C2 can significantly improve the tribological performance of M50-Sn-Ag-Cu-Ti3C2, reduce the intensity of frictional noise and suppress its high-frequency components. Frictional noise is caused by the system energy dissipation due to the contact surface roughness. The synergistic effect of Ti3C2 and Sn-Ag-Cu makes the lubricant be easily extruded to the contact surface, which will form a protective layer on the worn surface, thus reducing the surface roughness and frictional noise and improving the tribological performance. [ABSTRACT FROM AUTHOR]

In view of the uneven lubricating film of M50 aviation bearings under high load, it is of great significance to explore how to improve its friction performance through the synergistic lubrication of solid lubricant and lubricating oil. Inspired by the material transport of leaf veins, a bionic microchannel was designed for the contact interface. M50, M50-SnAgCu (MS) and M50-SnAgCu-Nb2C (MSN) biomimetic composites are prepared, respectively. The tribological properties of the material under dry friction and three grades of Mobil oil (DTE 24, DTE 25 and DTE 26) were investigated through ball-on-disk friction. The high-hardness Si3N4 ball is used as the counterpair. The results show that the average friction coefficient and wear rate of MSN are reduced by 29.63% and 28.36%, respectively. In addition, the furrows on the worn surface were significantly reduced. The synergistic lubrication of SnAgCu-Nb2C and the DTE 26 oil makes M50 have a excellent antifriction and wear resistance. The results can provide guidance for the research of synergetic lubrication behavior of materials. [ABSTRACT FROM AUTHOR]

Improving the tribological properties and reducing the friction noise of Inconel 625 is of great significance for the extended application of Inconel 625 in mechanical parts and other fields. In this paper, composite anti-wear surfaces (CASs) with micro-texture filled by Sn-Ag-Cu (SAC) were prepared. The tribological and frictional noise properties of CASs and smooth surface (SS) with different texture spacing during dry sliding friction process were studied through a series of experiments, tests and analyses. The results show that CASs can improve tribological properties and noise suppression performance significantly. With the texture density of 25 % (CASs-1200), the friction coefficient is 0.464 under a load of 20 N, the wear rate is about 2.65×10−5 mm3/(N·m), and the friction noise is 88-89.5 dB. Due to the synergistic effect of surface microgrooves and solid lubricants, the excellent tribological performance of CASs was realized. Microgrooves make the lubricant mixture be easier precipitated onto the worn surface. An intact lubrication film with high shear fitness was formed on the worn surface, reducing the direct contact between the grinding ball and the substrate. Meanwhile, it reduces the radiated energy generated by the collision between the counterpart ball and matrix and the transition of counterpart ball on the uneven small platform, so as to achieve the effect of noise suppression. Especially, suppression effect of high-frequency noise in 2400-3000 Hz is close to 100 % in CASs-1200, inhibiting the high-frequency scream effectively. [ABSTRACT FROM AUTHOR]

Workpiece will face corrosive problems during its application after the manufacturing process. As the common final process, grinding can generate special metamorphic layer on the surface of workpiece and change the initial corrosion resistance of workpiece. In order to study the corrosion resistance of workpiece after grinding process, the paper carries on combining experiment of grinding and electrochemical corrosion. The characteristic of corrosion resistance of grinding is revealed based on the association of grinding mechanism and electrochemical theory. The corrosion potential of workpiece after grinding is higher than matrix, which shows the grinding surface is difficult to begin to corrode. Electrochemical impedance spectroscopy (EIS) shows the grinding surface has large phase angle, impedance and capacitance characteristic because the metamorphic layer of grinding has good obstructive ability. They reveal that grinding improves the surface corrosion resistance of workpiece. Then the mechanism of the corrosion resistance of grinding is revealed. The special grain boundary formed in grinding with much C element, large clusters and complex shape prolongs the corrosion channel, which reduces the corrosive speed. While, the sensitive hardening structure generated in grinding hardening with much free energy is easy to form the corrosion cell, which will accelerate the corrosion. [ABSTRACT FROM AUTHOR]

The poor tribological performance of TC4 alloy limits its wide application in engineering field. Inspired by the layered structure of shell, the bionic composite coating of TC4-SnAgCu (TSAC) on TC4 was designed. The coatings with three different lubricant concentration ratios of TC4-5wt.%SnAgCu (TSAC-5), TC4-10wt.%SnAgCu (TSAC-10) and TC4-15wt.%SnAgCu (TSAC-15) were prepared using laser additive manufacturing (LAM) technology, respectively. Tribological tests were, respectively, carried out at the loads of 10 N, 15 N, 20 N and 25 N. The results show that compared with TC4, TC4 with bionic coating has better tribological behaviors and reducing ability of friction-induced vibration and noise. Furthermore, at 20 N and room temperature, the complete lubrication film is more easily formed on the worn surface of TSAC-10. Hence, TSAC-10 obtains the minimum friction coefficient and average equivalent noise pressure, which are, respectively, reduced by 21.28 % and 18.76 % compared to those of TC4. [ABSTRACT FROM AUTHOR]

The bionic rhombic textures with SnAgCu and Nb2C were used to improve tribological properties of M50. Compared with M50, friction coefficient and wear depth of M50-SnAgCu-Nb2C with 45° textures at 15 N were separately decreased by 42.67 and 70.37%, and those of M50-SnAgCu-Nb2C with 60° textures at 25 N were, respectively, decreased by 42.04 and 65.03%. Nb2C can promote the combination and spread of composite lubricants in bionic textures, and a uniform and dense lubrication layer was formed at the interface. The synergistic effect of SnAgCu-Nb2C and bionic textures can play an excellent antifriction and wear resistance role under specific working conditions. [ABSTRACT FROM AUTHOR]

Improving the friction-induced noise suppression performance of TC4 has far-reaching significance for its wide application in the field of robots and semiconductors. The friction noises of TC4 with solid lubricant (Sn-Ag-Cu) filled into dimples (TCS) and TC4 were predicted by simulation analysis. The noise reduction performance of TCS during dry rotary sliding was discussed. TCS with dimple size of 0.6 mm (TCS-0.6) exhibited the prominent performance of noise reduction, which was attributed to the synergistic effect of dimples and solid lubricant. During the dry sliding process, the debris were contained by dimples, the stress distribution in matrix was modified by lubricant, and the defects were decreased. Hence, the roughness of worn surface was reduced, which was beneficial to obtaining the stable friction coefficient. Inhibiting the unstable vibration by controlling the friction coefficient of the system can effectively demote the friction-induced noise. [ABSTRACT FROM AUTHOR]

Background: Cholangiocarcinoma (CCA) is a rare malignant tumor of the biliary system. The heterogeneity of CCA leads to the lack of effective targeted treatment for CCA subtypes. The molecular characteristic of hilar CCA (hCCA) is still unclear. Methods: A total of 63 hCCA patients were enrolled from Shanghai Eastern Hepatobiliary Surgery Hospital. Formalin-fixed, paraffin-embedded tumor tissues, and matched blood were collected and deep sequencing targeting 450 cancer genes were performed. Tumor mutation burden (TMB) was measured by an algorithm developed in-house. Correlation analysis was performed by Fisher's exact test. Results: The most commonly mutated genes were TP53 (51.7%), NF1 and KRAS (20%, for both), SMAD4 (16.7%), FAT3 and FRS2 (13.3%, for both), NF1 (11.7%), and KMT2C, MDM2, and ATM (10%, for each) in hCCA. ARID1A, GATA6, and PREX2 mutations commonly occurred in female and KMT2C mutations mainly occurred in patients under 60 years old. Statistical analysis showed the association between ARID1A mutation and tumor stage (P = 0.041) and between NF1 mutation and high TMB (P = 0.0095). Furthermore, ARID1B mutation was identified to associate with the poor prognosis of Chinese hCCA patients (P = 0.004). Conclusion: The mutational characterization of hCCA is different from both extrahepatic CCA and intrahepatic CCA. ARID1B is a potential biomarker for prognosis prediction of Chinese hCCA patients. [ABSTRACT FROM AUTHOR]

Ovarian cancer is one of the most common cancers in women and is often diagnosed as advanced stage because of the subtle symptoms of early ovarian cancer. To identify the somatic alterations and new biomarkers for the diagnosis and targeted therapy of Chinese ovarian cancer patients, a total of 65 Chinese ovarian cancer patients were enrolled for detection of genomic alterations. The most commonly mutated genes in ovarian cancers were TP53 (86.15%, 56/65), NF1 (13.85%, 9/65), NOTCH3 (10.77%, 7/65), and TERT (10.77%, 7/65). Statistical analysis showed that TP53 and LRP1B mutations were associated with the age of patients, KRAS, TP53, and PTEN mutations were significantly associated with tumor differentiation, and MED12, LRP2, PIK3R2, CCNE1, and LRP1B mutations were significantly associated with high tumor mutational burden. The mutation frequencies of LRP2 and NTRK3 in metastatic ovarian cancers were higher than those in primary tumors, but the difference was not significant (P = 0.072, for both). Molecular characteristics of three patients responding to olapanib supported that BRCA mutation and HRD related mutations is the target of olaparib in platinum sensitive patients. In conclusion we identified the somatic alterations and suggested a group of potential biomarkers for Chinese ovarian cancer patients. Our study provided a basis for further exploration of diagnosis and molecular targeted therapy for Chinese ovarian cancer patients. [ABSTRACT FROM AUTHOR]

High wear is the primary failure mechanism of Inconel 625 in mechanical parts. The surface modification is workable method to improve tribological performance of Inconel 625. In this paper, the groove-textured surfaces with different widths and pitches were prepared on the surfaces of Inconel 625 by electrical discharge machining technology. The Sn-Ag-Cu solid lubricant was deposited on the grooves. The synergistic effects of Sn-Ag-Cu solid lubricant and groove-textured surface on the tribological performance of Inconel 625 were studied. Results show that the groove-textured surface of Inconel 625 filled with Sn-Ag-Cu solid lubricant shows the lowest friction. Compared with the untextured sample, the friction coefficients of groove-textured sample with the groove density of 20% and the groove-textured sample with the groove density of 25% filled by Sn-Ag-Cu are reduced 35% and 48%, respectively. The textures can trap wear debris under the dry sliding condition. In addition, Sn-Ag-Cu alloys filled in the grooves supply the sufficient lubricant at the contact interface during the sliding process. The lubricating film on the contact surface is formed gradually, which is mainly due to the shear adaptability and low melting point of Sn-Ag-Cu alloy. It shows that deposition of Sn-Ag-Cu solid lubricant coating on the groove-textured surface is an effective way for improving the friction and wear performance of Inconel 625. [ABSTRACT FROM AUTHOR]

Lung cancer is the leading causes of cancer-related death worldwide. Precise treatment based on next-generation sequencing technology has shown advantages in the diagnosis and treatment of lung cancer. This cohort study included 371 lung cancer patients. The lung cancer subtype was related to the smoking status and sex of the patients. The most common mutated genes were TP53 (62%), EGFR (55%), and KRAS (11%). The mutation frequencies of EGFR, TP53, PIK3CA, NFE2L2, KMT2D, FGFR1, CCND1, and CDKN2A were significantly different between lung adenocarcinoma and lung squamous cell carcinoma. We identified the age-associated mutations in ALK, ERBB2, KMT2D, RBM10, NRAS, NF1, PIK3CA, MET, PBRM1, LRP2, and CDKN2B; smoking-associated mutations in CDKN2A, FAT1, FGFR1, NFE2L2, CCNE1, CCND1, SMARCA4, KEAP1, KMT2C, and STK11; tumor stage-associated mutations in ARFRP1, AURKA, and CBFB; and sex-associated mutations in EGFR. Tumor mutational burden (TMB) is associated with tumor subtype, age, sex, and smoking status. TMB-associated mutations included CDKN2A, LRP1B, LRP2, TP53, and EGFR. EGFR amplification was commonly detected in patients with acquired lcotinib/gefitinib resistance. DNMT3A and NOTCH4 mutations may be associated with the benefit of icotinib/gefitinib treatment. [ABSTRACT FROM AUTHOR]

Improving the tribological performance of TC4 has far-reaching significance for its wide application in the field of automobile and robot. The lubricating behaviors of TC4 with mixed solid lubricant (Sn-Ag-Cu with TiC) filled into surface dimples (TAC) during dry rotary sliding were systematically investigated. The results show that TAC has better tribological properties than TC4 and TC4-P. It attributes to the synergistic effect of surface dimples and mixed solid lubricant. The mixed solid lubricant in dimples is easier to be extruded to the frictional interface. The uniform and wear-resistant lubricating layer containing SAC and TiC is formed on the worn surface of TAC, reducing the direct impact of counterpart ball on substrate material. The fluidity of SAC endows TAC with the ability of self-repairing. [ABSTRACT FROM AUTHOR]

Based on the microporous structure lubrication method, Ti6Al4V(TC4)-based self-lubricating composites (TC4-SAC) with microporous channels filled by lubricant Sn-Ag-Cu are prepared. The effects of microporous channel parameters on stress and deformation of TC4-SAC are analyzed by finite element method. In addition, the friction and wear behaviors of TC4-SAC with different microporous channel parameters are compared, and the self-lubricating mechanisms of TC4-SAC are also analyzed. The results show that microporous channel parameters have a significant influence on the mechanical and tribological performance of TC4-SAC. Moreover, when the vertical depth of microporous channel = 3.5 mm, the micropore pitch = 3 mm, and the micropore diameter = 0.8 mm, TC4-SAC can obtain the best mechanical property and self-lubricating characteristic. [ABSTRACT FROM AUTHOR]

To overcome the poor tribological performance of M50 and widen its working range under high temperature, M50-Sn-Ag-Cu composites with curved microchannels (MCCs) and straight microchannels (MCSs) were prepared by Laser Additive Manufacturing Technology, respectively. Tribological properties of M50-based composites were studied. The results showed that MCCs had the better tribological performance. At 25 °C-15 N-0.2 m/s, compared with MCSs, the average friction coefficient of MCCs at the stable friction stage was reduced by 10.7%. In contrast to MCSs, MCCs had a wider operating temperature range than MCSs, and the average friction coefficient of MCCs was decreased by 23.4 at.% 350-450 °C. According to the simulation results, the lubricant expansion of MCCs was 1.56 times that of MCSs at 400 °C. The curved microchannels design makes the storage and formation capacities of the lubricating film be enhanced without weakening the bearing capacity of MCCs. The two-way opening design of the curved microchannels could reduce the stress concentration between lubricant and friction interface, hence ensuring the efficient precipitation of lubricant. The research work could have a guiding role for widening the temperature range of M50 composites and improving the reliability of high-end equipment bearing. [ABSTRACT FROM AUTHOR]

The workpiece surface obtains the fine machining during the grinding as well as the impacting effect of grinding wheel, which causes the changing of its hardness. In order to predict the hardness of structural steel workpiece after grinding, the paper established an approximate hardness model of workpiece after grinding by establishing a calculating method for the cooling condition, the model of grinding strain, and the correlation between the equivalent strain and hardness. The hardness value and distribution of hardness field of grinding were predicted by the method with accuracy relatively. The variation and influencing mechanism of hardness along with grinding parameters were studied. And dynamic hardness field of the model revealed the dynamic recovery and recrystallization during grinding. A grinding experiment verified the accuracy of the model approximately. [ABSTRACT FROM AUTHOR]

Friction noise will not only affect the life of equipment, but also endanger human health. It is imperative to reduce the friction noise of mechanical system. Tribological properties and friction noise of Ti6Al4V alloy (TC4) and Ti6Al4V-4.6 wt.% MoS2-3.7 wt.% TiC (TMT) self-lubricating composites under 5, 10 and 15 N at 0.2 m/s are investigated using a self-built friction noise experimental apparatus. The results show that MoS2 and TiC have the good synergistic effects on tribological and friction noise performance. A lubricating film enriched with MoS2 is formed on the worn surface to reduce the stick–slip and surface roughness, and the energy of transition on the worn surface is reduced; hence, the friction noise is decreased. TiC can improve the hardness and wear resistance of TMT, and it supports the lubricating film to hinder the development of plowing grooves and peeling pits to a deeper level. The worn surface and friction noise performance of TMT are best at 10 N. This study has the far-reaching implications for improving the tribological properties and inhibiting friction noise of TC4 alloys. [ABSTRACT FROM AUTHOR]

Ti6Al4V alloy has broad application prospects in the aircraft industry. However, when it is served as frictional motion components, the poor friction and wear properties may greatly influence the reliability and working life of the entire mechanical system. Therefore, this paper mainly investigates the tribological performance and self-repairing functionality of Ti6Al4V-multilayer graphene (MLG)-Ag composites (TMAC) from 25 to 600 °C. The results show that TMAC obtains better tribological behavior in comparison with Ti6Al4V alloy (TC4), Ti6Al4V-MLG composites (TMC) and Ti6Al4V-Ag composites (TAC). It should be ascribed to the synergistic action of the reinforcement MLG and lubricant Ag, which are crushed and spread out by mechanical and thermal stress in the friction process, leading to the formation of a lubricating film on the wear scar. Along with the spreading of lubricating film, Ag and MLG can precipitate onto the microdefective areas, thus playing an important role in repairing the wear scar of TMAC. [ABSTRACT FROM AUTHOR]

As one of the most widely used high-performance bearing steels, the service life of M50 steel is closely related to its tribological properties. In this paper, the dry sliding tribological tests of M50 matrix composite containing 5.0 wt.% Ag and 5.0 wt.% carbon fiber (CF) against Si3N4 ceramic balls are carried out under different applied loads. The morphologies and compositions of worn surfaces and the cross sections of worn scars are systematically characterized to explore the wear mechanisms. The results indicate that M50-Ag-CF composites (MAC) exhibit the excellent tribological properties at 10 N, whose friction coefficient and wear rate are 0.212 and 1.6 × 10−6 mm3 N−1 m−1, respectively. The excellent tribological performance can be attributed to the synergistic effect of Ag and CF. Massive Ag is enriched on the friction surface to form a lubricating film, thus reducing the surface roughness and friction coefficient. Meanwhile, CF acts as a reinforcement and improves the wear resistance of M50 matrix composites. [ABSTRACT FROM AUTHOR]

As the main steel used in the aero-engine main shaft bearings, the tribological properties of M50 can directly affect the performance of aero-engine. The purpose of this study is to design the reasonable composition of Sn-Ag-Cu alloy and investigate the wear mechanisms of M50-10 wt.%(Sn-Ag-Cu) composites (MSACC) prepared by SPS sliding against Si3N4 ball from 25 to 550 °C at 12 N-0.25 m/s. XRD, EPMA, FESEM and EDS mappings are conducted to understand the major mechanisms leading to the improvement in the sliding behavior of MSACC. The results indicate that MSACC with different specifications of Sn-Ag-Cu alloy shows excellent friction and wear properties from 25 to 550 °C compared to M50. M50-10 wt.%(50Sn40Ag10Cu) (MSACC-2) shows the distinguished tribological performance for the lower friction coefficients of 0.22-0.61 and less wear rates of 1.7-4.1 × 10−6 mm3 N−1 m−1, which is attributed to the formed excellent lubricating structure consisting of the lubricating film with massive Sn-Ag-Cu alloy and intermetallic compounds formed during the friction process, as well as the underneath mixed layer who can well support the lubricating film due to the good intersolubility between the designed Sn-Ag-Cu alloy and M50 (Fe). [ABSTRACT FROM AUTHOR]

M50 steel is widely used in aero-engine bearings and other high-temperature bearings. However, the poor wear of M50 steel resistance restrains its further applications. In this paper, the sliding tribological behaviors of M50 steel, M50-Ag composites (MAC) and M50-Ag-TiC composites (MATC) against Si3N4 ball were investigated from 150 to 600 °C at 15 N-0.2 m/s. MATC showed better tribological properties in comparison with M50 and MAC. Especially at 450 °C, MATC obtained the lowest friction coefficient of 0.15 and smallest wear rate of 1.3 × 10−5 mm3 N−1 m−1. The excellent tribological performance of MATC during the friction test was attributed to the continuous lubricating film containing lubricant Ag and reinforcement TiC, as well as the subsurface compacted layer that could well support the lubricating film to prevent it from being destroyed. At 600 °C, because of the tribo-chemical reaction between Ag and Mo oxide during sliding process, the newly formed Ag2MoO4 lubricating film was well spread out on the friction surface, which could continuously improve the tribological behavior of MATC. This investigation was meaningful to improve the anti-friction and wear resistance of M50 matrix bearing over a wide temperature range. [ABSTRACT FROM AUTHOR]

In order to study the effect of scanning velocity on the microstructure and tribological properties of Ni3Al matrix composites containing graphene nanoplatelets (NGs), a series of NG samples are successfully synthesized by laser melt deposition under the various scanning velocities from 300 to 500 mm s−1. The sliding friction tests of NG against GCr15 steel balls are carried out under 10 N and 0.2 m s−1 at room temperature. The microstructures, tribological properties and wear mechanisms of the NG samples are analyzed. The results show that the scanning velocity can be optimized to effectively control the surface hardness and relative density, as well as tribological performance of NG. The NG sample synthesized under scanning velocity of 450 mm s−1 has a dense and fine microstructure as well as excellent properties such as higher relative density (98.6%), lower friction coefficient (0.23) and wear rate (5.5 × 10−6 mm3 N−1 m−1). The lower substrate layer with dense and stable structure plays an important role in supporting the upper glaze layer with rich graphene and oxides, as well as nanocrystalline structure, which contributes to the excellent friction-reducing and wear resistance performances of NG. The research results could be used to guide the selection of suitable scanning velocity and study the wear mechanisms of NG for having excellent tribological performance. [ABSTRACT FROM AUTHOR]

M50 steel is widely applied to manufacture aircraft bearings where service lives are mainly determined by the friction and wear behaviors. The main purpose of this study is to investigate the tribological behaviors and wear mechanisms of M50-1.5 wt.% graphene composites (MGC) prepared by laser additive manufacturing (LAM) (MGC-LAM) sliding against Si3N4 ball from 25 to 550 °C at 18 N-0.2 m/s. XRD, EPMA, FESEM, and EDS mapping were conducted to understand the major mechanisms leading to the improvement in the sliding behavior of MGC-LAM. The results indicated that MGC-LAM showed the excellent friction and wear performance at 25-550 °C for the lower friction coefficient of 0.16-0.52 and less wear rate of 6.1-9.5 × 10−7 mm3 N−1 m−1. Especially at 350 °C, MGC-LAM obtained the best tribological performance (0.16, 6.1 × 10−7mm3 N−1 m−1). It was attributed to the dense coral-like microstructure, as well as the formed surface lubricating structure which is composed of the upper uniform lubricating film with massive graphene and the underneath compacted layer. [ABSTRACT FROM AUTHOR]

In order to improve tribological performance of NiAl-based alloy, NiAl matrix composites containing 1.5 wt.% multilayer graphene (MLG) are prepared through additive manufacturing (AM) and spark plasma sintering (SPS), which are denoted as NMAM and NMSPS, respectively. Tribological behaviors of NMAM and NMSPS against SiN balls are researched under constant speed (0.2 m/s) and varied loads (from 4 to 16 N) for evaluating the tribological properties of NMAM and NMSPS. The results present that NMAM exhibits the excellent tribological properties [low friction coefficients (0.26-0.40) and considerable wear resistance (2.8-4.6 × 10 mm N m)] as compared to NMSPS, which attributes to the uniform enrichment of MLG with properties of high tensile strength and being easily sheared off on the worn surfaces. Owing to the use of spherical prealloyed powder containing multilayer graphene and the characteristics of layer by layer depositing in the AM process, NMAM has a more compact and uniform substrate, which persistently provides a source of the formation of continuous and stable frictional layer. Due to the characteristics of AM rapid solidification, NMAM has the small grain size and well-compacted microstructure, which can effectively reduce the probability of spalling wear and lead to the increase in wear resistance of materials. The research can offer the reference for self-lubricating materials prepared by AM technology. [ABSTRACT FROM AUTHOR]

This article was dedicated to explore the combined lubrication of silver, MoS and carbon nanotubes (CNTs) based on the changes in applied loads and sliding speeds. The results showed that the formed lubricating films played the major role in undertaking the equivalent stress, as well as effectively reduced friction resistance and material loss. It led to small friction coefficient and less wear rate at 1.2 m/s. At 1.2 m/s-16 N, an integrated lubricating film containing Ag, CNTs and MoS was continuously formed, which well provided the excellent lubricating property, resulting in lower friction coefficient (0.19) and less wear rate (1.56 × 10 mm/N m). The formation of Ag and CNTs enriched islands acted as the bearing areas and played the major role in resisting friction resistance. Meanwhile, solid lubricant MoS was enriched in the lubricating film and effectively protected lubricating film from being destroyed, resulting in small friction coefficient and less wear rate at 1.2 m/s-16 N. [ABSTRACT FROM AUTHOR]

Hardening layer with a certain thickness can be formed on the workpiece surface after grind-hardening process. It can provide a better using performance for the workpiece. Therefore, the study on surface hardening layer and its distribution has important meaning to improve the using performance of the workpiece after dry grinding process. The paper analyzed the hardness, thickness, and its consistency of hardening layer through grind-hardening experiment using 40Cr and 45 steel. And then the paper studied the temperature field of surface hardening layer on the workpiece by FEM simulation. The cooling rate v could be calculated by using temperature-time curve. The distribution of hardness and thickness of surface hardening layer was also obtained. Combined with experiment results, the characteristic of the consistency of surface hardening layer was analyzed. The result showed that the hardness of the surface hardening layer would increase with the increasing of depth of cut a and feeding rate v . The thickness of the surface hardening layer also increases with the increasing of a , but it decreases with the increasing of v . The Cr element benefited the formation of martensite when the depth of the cut is small. But when the depth of the cut reaches to a certain value, the effect of Cr element could no longer be obvious. The results also showed that the consistency of intermediate area on the workpiece is much better than that of the cutting-in area and cutting-out area. Therefore, in order to obtain surface hardening layer with the suitable hardness and thickness, both technological parameters and materials should be chosen appropriately. [ABSTRACT FROM AUTHOR]

The dry sliding friction and wear behaviors of TiAl matrix self-lubricating composite (TMSC) containing multilayer graphene (MLG), silver (Ag) and MLG-Ag sliding against SiN balls from 25 to 750 °C were comparatively studied in this paper. The results suggested that TMSC containing MLG-Ag (TMA) showed better tribological properties over the wide temperature range, if compared to TMSC only containing MLG or Ag. Moreover, TMA exhibited the lower fiction coefficient and the less wear rate at 450 °C, which was attributed to the formation of intact lubricating films containing MLG and Ag on the worn surface. Furthermore, in the formed lubricating films, Ag worked as the solid lubricant to provide good lubricating effect, while MLG with high strength played the active role in enhancing the anti-rupture ability of lubricating films. The study indicated that TMA obtained the excellent tribological performance at 450 °C due to the remarkable synergistic effect of MLG and Ag. [ABSTRACT FROM AUTHOR]

The application of NiAl-based alloy (NA) in the field of aerospace was limited by its poor tribological properties. For improving the tribological performance of NA, multilayer graphene (MLG) and TiSiC were added in NiAl matrix composites. Tribological behavior of NiAl matrix composites containing 1.5 wt.% MLG and 10 wt.% TiSiC (NMT) against SiN ball at 12 N-0.2 m/s from 25 to 750 °C was investigated. The results showed that NMT exhibited the excellent tribological behavior [lower friction coefficients (0.26-0.57) and less wear resistance (3.1-6.5 × 10 mm N m)] due to synergetic effect of MLG and TiSiC over a wide temperature range from 25 to 750 °C. At 25-350 °C, part of MLG enriched on worn surface could play a role in reducing friction and improving wear resistance. At 350-550 °C, although MLG gradually lost the lubricating properties, the partial decomposition of TiSiC could continually improve the tribological properties of NMT. At 550-750 °C, TiSiC on worn surface was oxidized to form lubricating film, while TiSiC in the subsurface played an important role in supporting the film, resulting in the excellent high-temperature tribological performance. The research had good guiding significance for the preparation of wide temperature range self-lubricating material and the study of synergetic effect of complex solid lubricants. [ABSTRACT FROM AUTHOR]

The tribological performance is a key factor for M50 steel that is widely used in aero-engine main-shaft bearings. In this study, the tribological properties of M50 matrix self-lubricating composites with different contents of TiSiC against SiN ceramic counterpart are investigated at 15 N-0.2 m/s from 25 to 450 °C. The results showed that M50 with 10 wt.% TiSiC (MT10) exhibits the lower friction coefficients (0.21-0.78) and less wear rates (1.78-3.14 × 10 mm N m) at 25-450 °C. Especially at 350 °C, MT10 shows the lowest friction coefficient and wear rate owing to the formation of smooth lubricating layer containing TiSiC and oxides. TiSiC and compacted Ti-Si-oxides are uniformly distributed in the lubricating layer, which can well improve the anti-friction and anti-wear performance of MT10. The mechanically mixed layer containing massive TiSiC can sustain the lubricating layer, resulting in the increase of anti-wear performance of MT10. MT10 could be applied under the practical conditions of friction and wear for its outstanding anti-friction and anti-wear performance. [ABSTRACT FROM AUTHOR]

In this investigation, the effect of TiC particulate reinforcement and sintering parameters on tribological behavior of TiAl metal matrix composite (TMMC) has been studied and compared with commercially conventional gray cast iron to evaluate the use of TMMC as brake disk material in an automobile. Three sample disks of TMMC containing TiC particulate reinforcement (D1-5 wt.%, D2 and D3-10 wt.%) were produced by the spark plasma sintering process. D3 compared with D2 was sintered at a higher temperature to evaluate the effect of SPS parameters on the wear characteristics of TMMC. All experiments were performed on pin-on-disk tribotester under a dry sliding condition with different loads (10-11.5 N) and sliding velocities (0.2-0.9 m/s). It is found that higher content of TiC increased TMMC hardness and density. XRD technique has been used to analyze the phase composition. Owing to the high sintering temperature, α-2 TiAl phase was formed which further enhanced the matrix anti-wear capability. Scanning electron microscope (SEM) was used to capture the wear track and observe wear mechanism. Energy-dispersive spectroscopy (EDS) has been used to analyze the tribofilm and wear debris. The results showed that the tribofilm for TMMC was mainly composed of metal oxides. Oxidation of Al and Ti due to frictional heat provides wear-resistant protective layer. Under almost all sliding conditions, TMMC, especially disk D3, exhibited minimum wear rate and stable friction coefficient, whereas gray cast iron exhibited lower and unstable friction coefficient as well as higher wear rate. TMMC has shown superior tribological characteristics over gray cast iron in terms of low wear rate along with stable and adequate friction coefficient which is necessary for braking operation and life of brake disk. However, further investigation on full-scale automobile conditions is needed for its practical application. [ABSTRACT FROM AUTHOR]

In this study, the effect of friction layer thickness and subsurface nano-hardness of wear track on tribological behavior of γ-TiAl matrix composites is investigated. The results of dry sliding tribolocial tests of γ-TiAl matrix composites with 0-2.25 wt.% multilayer graphene (MLG) (0.25 wt.% in tolerance) under different applied loads are reported. The testing results show that the optimized addition amount of MLG is 1.75 wt.% at 12 N (friction layer thickness 3.23 µm, subsurface nano-hardness of wear track 9.03 GPa). It can be found that a continuous and thick friction layer is formed in γ-TiAl-1.75 wt.% MLG at 12 N, resulting in a lower friction coefficient of 0.31 and wear rate of 2.09 × 10 mm N m. During dry sliding process, the high subsurface nano-hardness of wear track leads to the increase in resisting plastic deformation capacity and reduces the material loss. Meanwhile, the thick friction layer contains MLG with high tensile strength which is easily sheared off. Hence, γ-TiAl matrix composites show excellent tribological performance of a friction-reducing and an increase in wear resistance. The investigation shows that γ-TiAl-1.75 wt.% MLG, due to its excellent tribological behavior at 12 N, can be chosen as a promising structural material for minimizing friction- and wear-related mechanical failures in sliding mechanical components. [ABSTRACT FROM AUTHOR]

Tribological behaviors of TiAl-multilayer graphene-microsphere composites (TMMC) are investigated at different loads in this paper. The tribological results show that TMMC exhibit excellent wear and friction performances from 4 to 20 N for the formation of the intact and smooth tribo-films containing multilayer graphene (MLG) and WS-SiO microsphere (WSM) on the worn surfaces. During the sliding process, MLG and WSM are ground out of TMMC to form the tribo-films on the worn surfaces, which is beneficial to the decreasing in friction coefficients and wear rates. MLG is easy to be sheared for the weak interlayer binding force, which can reduce the friction coefficients and wear rates. WSM can repair the tribo-film by filling its worn pits, resulting in the smooth worn surface and excellent tribological performance of TMMC. Moreover, the hardness of TMMC is increased for the addition of MLG and WSM, which makes contributions to the improvement of tribological behaviors of TMMC. [ABSTRACT FROM AUTHOR]

In order to analyze the effects of friction layer thickness on the tribological performance of NiAl matrix self-lubricating composites containing Ag and MoO tabular crystals (NiAl-Ag-MoO), the dry sliding tribological tests of NiAl-Ag-MoO against SiN ball are undertaken under 4-16 N and 20-800 °C at 0.2 m/s. The results show that the friction layer thickness of NiAl-Ag-MoO is obviously affected by the applied loads and ambient temperatures. At 12 N-400 °C-0.2 m/s, NiAl-Ag-MoO exhibits excellent tribological performance, and the friction layer thickness obtained the maximum value of about 5 µm. Moreover, the simulation results, which based on the building of finite element models with different thickness of the friction layer, indicate that the decreased degree of the maximum equivalent stress in the substrate of NiAl-Ag-MoO with maximum thickness of friction layer is the larger one (about 39%), if compared to other thickness. It could avoid the generation of cracks and the spalling of subsurface materials during the dry sliding process, resulting in the excellent tribological performance. The results could be used to guide the selection of suitable working conditions and study the self-lubricating mechanisms of NiAl-Ag-MoO for having stable friction layer structure and excellent antifriction and antiwear performance. [ABSTRACT FROM AUTHOR]

Grind-hardening is a new technology for steel part surface enhancing which uses thermal and mechanical composite effects on the parts in the grinding process. During the process, the workpiece surface generates hardened layer that improves the surface quality. Hardened layer may enhance fatigue strength, friction and wear properties, and corrosion resistance of parts significantly. Since component properties are influenced greatly by hardness penetration depth and its uniformity of parts, prediction of hardness penetration depth is significant to the practical engineering. First, the part is divided into cutting-in zone, middle zone, and cutting-out zone along length direction according to the characters of heat source strength changes. The mathematical models for segmented triangle heat source are carried out. Moreover, ANSYS is applied to simulate and analyze the distribution of temperature field and the change of instantaneous temperature in each zone of the grinding process. And the hardening penetration depth in each zone is predicted accordingly. Study of mechanism of depth uniformity is conducted emphatically in this paper. Results show that the change of heat intensity makes both ends of part not hardened during the grinding process. Hardening penetration depth increases gradually in the cutting-in zone and decreases gradually in the cutting-out zone. Meanwhile, the middle zone acquires deep and uniform hardened layer. Finally, comparison between predicted value and experimental value is carried on to verify the validity of source optimization model and reasonableness of prediction methods. [ABSTRACT FROM AUTHOR]

The contact stresses of materials in moving mechanical assemblies are rather important for minimizing friction and decreasing machinery energy dissipation. In this study, the effect of contact stresses on the friction and wear behaviors of TiAl-10 wt.%Ag was studied at 0-240 min using the united methods of experiment research, numerical simulation and theoretical analysis. The results showed that the high contact stresses led to the plastic deformation of TiAl-10 wt.%Ag at 0-50 min. The friction coefficients and wear rates decreased rapidly with the lowering of contact stresses from 1034.28 to 710.52 MPa. At elastic deformation stage (50-240 min), the forming of lubricating film was beneficial to the decrease in friction coefficients and wear rates at 50-150 min, whereas the lower contact stresses caused the increasing of friction coefficients and wear rates. The competition between film lubrication and contact stresses caused the lowering of friction coefficients and wear rates at 50-150 min. At 150-240 min, the lubricating film maintained the equivalent lubricating behaviors, whereas the lowering of contact stresses led to the slight improving of friction coefficients and wear rates. This study was meaningful for optimizing applied loads to realize the excellent contact stress state and tribological behavior of mechanical parts. [ABSTRACT FROM AUTHOR]