Search

In the present study, the wear properties of 205 manganese steels produced by a casting process with different boron contents (0.0023-0.0182 wt.%) were investigated, using a pin-on-disc tribometer under dry sliding conditions. The friction coefficient of 205 manganese steel by boron addition (at 0.0076 wt.%) reduced from 0.28 to 0.18. The addition of boron to 205 manganese steel led to a decrease in the friction coefficient due to the lubricating effect of boron. X-ray diffraction showed that the boron addition to 205 manganese steel increased lattice parameters of the samples. The wear test results at 5 and 10 N loads showed that the wear amount of 205 manganese steels decreased with boron addition. Thus, the wear results showed that the wear resistance of 205 manganese steel is increased with the addition of small amounts of boron. Furthermore, scanning electron microscopy images indicated that the characteristic wear mechanisms for the boron-doped samples on the worn surfaces were abrasive, and it was plastic deformation, mild abrasive, and adhesive wear mechanism in the undoped 205 manganese steel.

In this study, Hardox 400 steel used as substrate material was coated through solid media Thermoreactive Diffusion (TRD) method using Ferro Niobium and Ferro Boron powders from carbide forming element powders. Coating was carried out in three different temperatures ([Formula: see text]C, [Formula: see text]C and [Formula: see text]C) and three different time intervals (1, 2 and 3[Formula: see text]h). Microstructures of the coated specimens were examined by optical microscope, Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDX) and X-ray Diffraction (XRD); and hardness values were measured. The effects of coating parameters on coating thickness and hardness were analyzed by ANOVA. In addition, specimens were subjected to wear tests to determine the effect of hardness and coating parameters on wear. In the wear tests, Taguchi test design setup was used. The obtained results were compared with the Hardox 400 steel used under current conditions. It was seen from optical microscope and SEM images that Hardox 400 steel surface could be coated with TRD method depending on coating parameters. The average thickness of NbC–B coating ranged from 1.797[Formula: see text][Formula: see text]m to 5.596[Formula: see text][Formula: see text]m under different process temperature and time. Rising the coating time and temperature increased the coating thickness by 311.40%. EDX analysis showed that the coating layer was composed of B, C, Fe and Nb elements, and XRD analysis also showed that the phase in the coating layer is NbC–B. The NbC–B phase was determined to be an important factor in increasing the hardness. The coating hardness is enhanced by 320.80% depending on the coating parameters. Optimum coating thickness, hardness and wear results were obtained from high coating temperature and time. Uncoated Hardox 400 steels were worn out more compared to the coated Hardox 400 steels. The contribution of coating temperature and time to wear resistance was 1.46% and 8.02%, respectively. It was observed that the important parameter for wear volume was the applied load.

Purpose With the condition monitoring system on airplanes, failures can be predicted before they occur. Performance deterioration of aircraft engines is monitored by parameters such as fuel flow, exhaust gas temperature, engine fan speeds, vibration, oil pressure and oil temperature. The vibration parameter allows us to easily detect any existing or possible faults. The purpose of this paper is to develop a new model to estimate the low pressure turbine (LPT) vibration parameter of an aircraft engine by using the data of an aircraft’s actual flight from flight data recorder (FDR). Design/methodology/approach First, statistical regression analysis is used to determine the parameters related to LPT. Then, the selected parameters were applied as an input to the developed Levenberg–Marquardt feedforward neural network and the output LPT vibration parameter was estimated with a small error. Analyses were performed on MATLAB and SPSS Statistics 22 package program. Finally, the confidence interval method is used to check the accuracy of the estimated results of artificial neural networks (ANNs). Findings This study shows that the health conditions of an aircraft engine can be evaluated in terms of this paper by using confidence interval prediction of ANN-estimated LPT vibration parameters without dismantling and expert knowledge. Practical implications With this study, it has been shown that faults that may occur during flight can be easily detected using the data of a flight without expert evaluation. Originality/value The health condition of the turbofan engine was evaluated using the confidence interval prediction of ANN-estimated LPT vibration parameters.

The thermal fatigue behavior of chromium vanadium carbide (Cr − V − C) coatings and the wear of the coatings after thermal fatigue cycling was studied. The Cr − V − C coatings were grown on the surface of a ductile iron using thermo-reactive diffusion (TRD) and subjected to thermal fatigue in the temperature range of 25 to 750 °C for up to 500 cycles. Characterizations were made using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, microhardness measurements and wear tests. The Cr − V − C coated samples displayed superior thermal fatigue and wear resistance compared to the untreated ductile iron, mainly due to the dissolution of graphite nodules in the vicinity of the surface during TRD. The dissolution of graphite reduced the possibility of failure initiating from graphite nodules and graphite-matrix interfaces. Increasing the number of cycles resulted in increased flaking and decreased wear resistance in both the Cr − V − C coatings as well as the untreated ductile iron. Although much of the Cr − V − C coating was lost (due to flaking) after thermal cycling, the absence of graphite near the surface still provided improved resistance to wear in the TRD-treated samples. The results of this study indicate that TRD coatings hold great promise for use in the industrial applications.

Ductile iron (DI) owes many of its attractive mechanical properties to the graphite nodules in its structure. However, since galvanic coupling can occur between the graphite nodules and the matrix in aggressive environments, these nodules can, at the same time, reduce its corrosion resistance. In this study, composite carbide coatings were grown on the surface of GGG-80 using the thermoreactive diffusion (TRD) process. The process was carried out at 900, 1000, and 1100 °C for 1 h using nanosized Fe-V and Fe-Cr powders. The coatings were characterized by X-ray diffractometry (XRD), two-dimensional profilometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and microhardness tests. The corrosion behavior of the coatings were evaluated in three different solutions (3.5 wt% NaCl, 5 wt% H2SO4, and 5 wt% HNO3) using electrochemical open-circuit potential (OCP) and potentiodynamic polarization measurements. Microstructures and hardness tests showed that the nodular graphite in the surface was dissolved at the TRD process temperatures and that a coating of 12–36 µm thickness and 2461–3200 HV0.05 hardness was obtained. The corrosion resistance of the composite coating was up to 10, 33.5, and 75 times higher than the uncoated GGG-80 in NaCl, H2SO4, and HNO3, respectively. The improvement in corrosion resistance was a direct result of the formation of complex carbides and the elimination of graphite nodules in the surface of the alloy.

In this study, Cr-V-C composite carbide layers were grown on the surface of a GGG-80 ductile iron using thermoreactive diffusion (TRD). The TRD process was carried out at temperatures of 900, 1000, and 1100 degrees C for 1 h using nano-sized Fe-V and Fe-Cr powders. The coatings were characterized by X-ray diffractometry (XRD), 2D profilometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), microhardness measurements, nanoindentation, and wear tests. The wear tests were performed on untreated and coated samples using a ball-on-disc type wear tester under 10 N load at four different temperatures (25 degrees C, 250 degrees C, 500 degrees C and 750 degrees C) against a 6-mm WC ball. Metallographic investigations revealed that the graphite nodules near the surface were dissolved as a result of the TRD process. Depending on the TRD process temperature, a coating with a thickness of 12-36 mu m, hardness of 24.14-31.38 GPa, and elastic modulus of 198-233 GPa was obtained. An increase in process temperature increased the thickness, hardness, and elastic modulus of the obtained Cr-V-C layers, which resulted in low friction coefficient values and decreased wear rates. Although all coated samples showed improved wear resistance in all wear test conditions, the wear rates were significantly increased at 750 degrees C due to flaking.

WOS: 000465193500040, In the current study, the surface of AISI D2 steel was coated with the powder blends of ferro-vanadium (Fe-V) and ferro-chromium (Fe-Cr). The coatings were performed using a thermo-reactive diffusion (TRD) treatment by the pack cementation method at three different temperatures (900 degrees C, 1000 degrees C, and 1100 degrees C) and three different durations (1 h, 2 h, and 3 h). The structural and mechanical characteristics of the coatings were compared between the treatment groups. For this aim, the types of the formed phases, the microstructure, the microhardness, the surface roughness, and the wear and friction performance of the coated samples were examined. XRD analysis found composite carbide coatings including chromium carbide (Cr-C), vanadium carbide (V-C), and chromium vanadium carbide (Cr-V-C). The coatings' thickness was 11.3-23.2 mu m, hardness was 2100-2500 HV, and average surface roughness (R-a) was 0.286-0.550 mu m, depending on the treatment condition. The vanadium containing phase contents of the coatings increased with the elevating coating temperatures. The formed composite coating layers caused a change in the appearance of wear track and wear mechanism on the material surface. After the coating process, there found to be a decrease in the friction coefficient as well as an improvement in the wear resistance up to 7 times. In the composite coating layers, the increase in V-C content in comparison to Cr-C led to an enhancement in wear resistance on the material surface.

WOS: 000526980900010, A two-step Thermo reactive diffusion processes (including an initial titatinizing step followed by boronizing) is proposed in order to obtain superhard complex TiBC coating layer on AISI D6 steel. Microstructural characterization and mechanical properties of obtained TiBC layer conducted by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), optical microscopy, 2D profilometer, X-ray diffraction (XRD), micro-hardness, nano-indentation hardness and ball-on disc wear tests. Wear tests were carried out in ball on disc device by applying 30 N load and 500 m sliding distance against WC abrasive ball. Microstructural studies revealed a compact, homogenous and crack-free TiBC layer with 0.29-1.91 surface roughness (Ra), 3.65-29.5 mu m thickness and 1800-4841 HV0.05, hardness and 146-235 GPa elastic modulus. Hardness values of TiBC layers was significantly higher than those obtained by standard titanizing and boronizing due to the interspersed TiB and TiC phases within the TiBC layer. Higher hardness values are highly effective on the wear resistance and wear type. Thus, in parallel with the increase in mechanical properties, wear resistance increased in the range of 4-120 times in comparison with the untreated AISI D6 sample. Severe wear and extensive plastic deformation was observed in the untreated AISI D6, while micro-cutting, micro-cracking and pitting was dominant in samples with hardness 1800-4000 HV. When the surface hardness reached values above 4000 HV the wear mechanism further changed to microcracking and spalling.

Glycogen storage disease type IV (GSD IV) is a rare autosomal recessive disorder caused by deficiency of the glycogen-branching enzyme (GBE). The diagnostic hallmark of the disease is the accumulation of a poorly branched form of glycogen known as polyglucosan (PG). The disease is clinically heterogeneous, with variable tissue involvement and age at onset. Complete loss of enzyme activity is lethal in utero or in infancy and affects primarily the muscle and the liver. However, residual enzyme activity as low as 5-20% leads to juvenile or adult onset of a disorder that primarily affects the central and peripheral nervous system and muscles and in the latter is termed adult polyglucosan body disease (APBD). Here, we describe a mouse model of GSD IV that reflects this spectrum of disease. Homologous recombination was used to knock in the most common GBE1 mutation p.Y329S c.986A > C found in APBD patients of Ashkenazi Jewish decent. Mice homozygous for this allele (Gbe1(ys/ys)) exhibit a phenotype similar to APBD, with widespread accumulation of PG. Adult mice exhibit progressive neuromuscular dysfunction and die prematurely. While the onset of symptoms is limited to adult mice, PG accumulates in tissues of newborn mice but is initially absent from the cerebral cortex and heart muscle. Thus, PG is well tolerated in most tissues, but the eventual accumulation in neurons and their axons causes neuropathy that leads to hind limb spasticity and premature death. This mouse model mimics the pathology and pathophysiologic features of human adult-onset branching enzyme deficiency.

In this study, AISI 304 austenitic stainless steel surface was boronized with nanoboron and ekabor-III powders at 950 and 1000°C for 2 and 4 hours period by solid-state box boronizing method. Then, behaviors of the boronized specimen in the microstructure, three-point bending, and tensile strength characteristics were investigated. As a result of the boriding process, the boride layer thickness in the range of 23–67 µm and microhardness value in the range of 1020–2200 HV have been obtained according to the increase in processing time and temperature and to the particle size of the boron source (0, 1). The coating layer on boronized specimens did not exhibit any sign of reaction caused by the tensile strength applied until the yield point was in both tests. Although the particle size of the boron agents was more effective on the boronized specimen’s bending and tensile strength behaviors, it was observed that processing temperature and its duration are effective as well.

Günümüzde otomotiv sektörü için büyüköneme sahip olan dayanım, hafiflik, ekonomiklik ve şekillendirilebilirlik istenenönemli özelliklerdendir. TRIP (Transformation Induced Plasticity) çeliklerideforme olabilen yüksek mukavemetli ideal fazları ile otomotiv sektörü için sonderece uygun bir yapı oluştururlar. Bu çalışmada, tipik TRIP çeliğinin mevcutalüminyum miktarı değiştirilerek vakumsuz indüksiyon ocağında farklı Aliçeriğine sahip TRIP çeliği üretimi gerçekleştirilmiştir. Üretimigerçekleştirilen TRIP çeliğinin Al oranı 0,4 – 0,8 ve 1,4 oranlarındadeğiştirilmiştir. Daha sonra, elde edilen numunelerin birleştirilmesinde MIG-MAG kaynak tekniği kullanılmıştır. Eldeedilmiş kaynaklı TRIP çeliklerinin, kaynak bölgesinin mikroyapı ve mikrosertlikprofilleri çıkarılmış ve elde edilen sonuçlar literatür ile karşılaştırılarakAl içeriğinin etkisi yorumlanmıştır., Strength, lightness, economy andformability are important characteristics for the automotive sector, which hasa high economic area today. TRIP (Transformation Induced Plasticity) creates ahighly suitable structure for the automobile industry with high strength idealphases which can be deformed. In this study, TRIP steel production withdifferent Al content carried out by adding Al in TRIP steel with usingnon-vacuum induction furnace. Al content of the steel was changed to 0,4 – 0,8and 1,4 ratios. Then, the obtained samples were combined with the MIG-MAGwelding technique.Microstructureand microhardness profiles of the welded TRIP steels were obtained and theresults were compared with the literature and Al content was interpreted.

TiC coatings on AISI D3 cold-work tool steel were carried out by pack method thermo-reactive diffusion process (TRD) for 2 and 4 h at 950, 1 000, 1 050 and 1 100 °C, respectively. The carbide layers were evaluated based on microstructure, thickness, hardness, energy dispersive X-ray facility and X-ray diffraction analysis. Titanium carbide layer thickness on the coated specimens ranged from 6 to 23 μm, depending on treatment time and temperature. Growth kinetics of the carbide layers were analyzed measuring the depth of carbide layer as a function of temperature and time. The activation energy was estimated to be 249.42 kJ/mol. The micro-hardness value of the coating layer was obtained to be 2 470 HV in maximum.

Soft tissue trauma is a type of acute traumatic ischemia. We investigated in this study whether the edema, inflammation and ischemia caused by the trauma could be affected positively by hyperbaric oxygen (HBO) and ozone therapy.Soft tissue trauma was generated in a total of 63 adult male Sprague-Dawley rats. Subsequently, rats were divided into three groups. The first group was treated with ozone, the second group with HBO, and the third group served as controls. Tissue and blood samples were taken at the end of the procedures. Tissue lipid peroxidation (LPO), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), inducible nitric oxide synthase (iNOS), heme oxygenase (HO)-1, and hypoxia-inducible factor (HIF)-1 levels were detected. Hematoxylin-eosin staining was used to determine the inflammation and edema histopathologically.We also detected HIF-1 activity, which decreases when the oxygen concentration increases, HO-1 activity, which has anti-inflammatory effects, and iNOS activity, which releases in any type of acute case. We determined a statistically significant reduction in iNOS and LPO levels in both the HBO and Ozone groups. A significant decrease in inflammation was detected in both the Ozone and HBO groups compared with the Control group, and a significant decrease in edema was detected in all three groups.We think that HBO and Ozone therapy have beneficial effects on biochemical and histopathological findings. Related clinical trials will be helpful in clarifying the effects.

In this study, corrosion behavior and mechanical properties of AISI 304 austenitic stainless steel, which was borided with Nanoboron powder, was investigated. The commercially available steel was subjected to a boriding treatment with a size of 10–50 nm Nanoboron powders, at the temperatures of 1223 K to 1273 K with boriding durations of 2 to 4 h. Microstructure characterization of the steel was carried out with optical microscopy, scanning electron microscopy, microhardness and X-ray diffraction analyses. Corrosion tests were made by static immersion into a 10% H2SO4 acid solution and weight loss calculations as well as salt spray tests were carried out in accord with the ASTM B-117 standard. Boriding thermal treatment, increased the corrosion resistance of the steel against the acid solution, up to about 4.3 times while in the salt spray tests, weight loss corrosion resistance increased up to tier 2. However, anti-corrosion resistance decreased by 40%, its untreated value.

Islah çeliklerden AISI 4140 çeliğinin otomobil-inşaat- ziraat makine parçaları, takım tezgahları, uçak parçaları, akslar, krank milleri ve dişliler gibi birçok kullanım alanları bulmaktadır. Çalışmada, 4140 çeliği 1640 ºC’de ergitilerek içerisine 17 ve 32 ppm bor ilave edilmiştir. Döküm sonrası elde edilen borsuz, 17 ve 32 ppm bor içeren 4140 çeliği (42CrMo4) haddelenmiş ve ısıl işlem için 980 ºC de 30 dakika bekletildikten sonra numunelere buzlu suda, normal suda, oda sıcaklığında ve fırında soğutma işlemi uygulanmıştır. Buzlu suda, normal suda, oda sıcaklığında ve fırında soğutma işlemi ile elde edilen numunelerin optik mikroskop ile mikroyapıları incelenmiştir. Ayrıca mikrosertlik ölçümleri gerçekleştirilmiş ve elde edilen sonuçlar literatür ile karşılaştırılarak tartışılmıştır.

In maintenance of aircrafts, engine health monitoring (EHM) method has crucial importance. If an aircraft engine is in good condition, aircraft accidents could be prevented. On the other hand, healthy engines enable reduced fuel consumption and maintenance costs. Most of the EHM methods track the exshaust gas temperature (EGT) value in evaluating the health level of an engine. In this study, both Levenberg-Marquardt Feedforward Neural Network and Radial Basis Function Network methods are used to estimate the EGT values. 15 inputs are utilized as aircraft flight performance parameters for estimating the output (EGT parameter) in the two models. Obtained results show us Levenberg-Marquardt Feedforward Neural Network is more efficient compared to Radial Basis Function Network in estimating the EGT. Using this method, engine deteriorations could be caught by pilots without any expert knowledge before more serious damages in aircraft engines.

In this study, Co-Cr-Mo powder was coated on the surface of AISI 304 stainless steel by the plasma transfer arc (PTA) process at 80, 90 and 100 A current values and argon gas was used for both plasma and protective. Deposition layers were examined with optical microscopy, SEM, EDX, XRD analysis and microhardness test. The thickness of the coating increased with current density. No cracks or pores were detected in the interface and coating layer. Higher current levels resulted in higher dilution levels and also in melting/burning of the substrate.

Porous NiTi shape memory alloy (SMA) was fabricated by self-propagating high-temperature synthesis (SHS). With this study, a new solution treatment “solution treatment under loading” was applied to porous NiTi SMA fabricated by SHS to determine microstructural improvement regarding single phase NiTi. The effect of solution treatment under load on chemical composition, constituent phases and phase transformation behaviors of the specimens was investigated and discussed. The chemical composition of the specimens considerably changed with solution treatment under loading. Intermetallic phases such as Ti 2 Ni and Ni 4 Ti 3 disappeared, the density of B2(NiTi) phase increased and phase transformation temperatures sharply decreased. Porous single phase B2(NiTi) SMA with high chemical homogeneity could be obtained by the load applied during solution treatment at 1050 °C.

In this study, the Ti–6Al–4V alloy was diffusion bonded to austenitic stainless steel at temperatures of 820, 885, 930 and 980°C, under a pressure of 5 MPa for 30 min. The effect of temperature on interface formations and microstructure was investigated using a scanning electron microscope (SEM), energy dispersive spectrograph (EDS) microanalyses, X-ray diffraction and shear strength of bonded specimens. The results showed that intermetallic phases and σ-phase formed in the interface region.

In this study, a martensitic stainless steel plate of 10 mm thick was welded by keyhole plasma transfer arc (PTA) welding technique both itself and using austenitic stainless steel plate of 2 mm thick in interface. So, penetration depth, microstructure, mechanical behavior and interface layer effects of keyhole plasma welding were investigated. After keyhole plasma welding, microstructural analysis including metallographic examination, and notch impact strength tests were performed. From the results, it was seen that with this technique can be obtained penetration depth of 8 mm without any pretreatment of welding. Also, austenitic stainless steel interface layer was raised impact strength of welding.

Porous NiTi shape memory alloy was fabricated by self-propagating high temperature synthesis. Effects of solution treatment under load applied on the microstructure were investigated. The densities of the phases changed insignificantly with solution treatment but the intermetallic phases such as Ti2Ni, Ni4Ti3 and Ni3Ti2 disappeared and the density of B2(NiTi) phase increased with the load applied during solution treatment. Consequently, porous NiTi SMA with ideal pore characteristics, high chemical homogeneity and high strength for hard tissue implants was obtained.

In this study, NiTi powder mixture was coated on the surface of an austenitic stainless steel (AISI 304) by plasma transferred arc (PTA). Coating was carried out by using 80, 90, 100 A current density under Ar atmosphere. Coating layer and interface were examined with SEM, EDX, XRD analysis and micro hardness test. Thickness of coating increased with current density. No cracks or pores were detected in the interface. Higher arc current densities caused a coating layer poor in NiTi alloy. Secondary phases such as Cr 2 Fe 7 Ni, Fe 7 Cr 2 Ni and Ni 3 Ti also formed in the coating layer.

In the present study, a high chromium white iron was diffusion bonded to an austenitic stainless steel, AISI 316L. The effects of bonding temperature and holding time at the reached temperature on microstructural developments across the joint region were investigated. After diffusion bonding, microstructural analysis including metallographic examination, energy dispersive X-ray (EDX), X-ray, microhardness measurements and shear strength was performed. From the results, it was seen that bonding temperature with holding time was effective on the formation of carbide (M3C) and width of the diffusion zone that affected the shear strength of the bonds.

In the present study, a duplex stainless steel and an austenitic stainless steel were diffusion bonded to medium carbon steel. The differences of two dissimilar metal couples at the test temperature on microstructural developments across the joint region were investigated. After diffusion bonding, microstructural analysis including metallographic examination, energy dispersive spectroscopy (EDS) and shear strength tests were performed. From the results, it was seen that mutual diffusion of C and Cr was effective on the morphology of the diffusion zone that affected the shear strength of the bonds.

In the present study, Ti-6Al-4V alloy was diffusion bonded to a ferritic stainless steel. The effect of bonding temperature on the microstructural development across the joint region was investigated. After diffusion bonding, microstructural analysis including metallographic examination, energy dispersive spectrograph (EDS) and shear strength was conduced. From the results, it was seen that bonding on the temperature was affecting the Fe and Ti mutual diffusion which controls the interface microstructure. The microstructure of the interface region was formed, consisting of Fe and Ti intermetallics. (c) 2006 Elsevier B.V. All rights reserved.

In the present study, an austenitic stainless steel and medium carbon steel were diffusion bonded. The effect of bonding temperature on microstructural changes and shear strength across the joint region was investigated by optical and scanning electron microscopy, energy dispersive spectroscopy and microhardness measurements. The results showed that the best joint free from microcrack and micovoids was obtained at 900°C with maximum shear strength of 475 MPa.

In the present study, a high chromium white iron was diffusion bonded to a low carbon steel. The effects of bonding temperature and holding time at the reached temperature on microstructural developments across the joint region were investigated. After diffusion bonding, microstructural analysis including metallographical examination, energy dispersive X-ray (EDX), wavelength dispersive X-ray (WDX), microhardness measurements and shear strength tests were performed. The results showed that bonding temperature with holding time was effective on the width of the diffusion zone that affected the shear strength of the bonds. As a result, from the microstructural observations, EDX and WDX analysis, microhardness measurements and shear strength tests, it was concluded that a high temperature with a long holding time must be used in the diffusion bonding of high chromium white cast irons to low carbon steels.

In the present study, a gray cast iron and a medium carbon steel couple were diffusion bonded at the temperatures of 850, 900, 950 and 1000 °C under a pressure of 8 MPa for 30 min, and the effects of temperature and high heating and cooling rate on interface formations and microstructure were investigated. After diffusion bonding, scanning electron microscopy, shear test measurements and microhardness measurement of interface region were made. The microstructure at the inside of medium carbon steel of bonded couple consisted of martensite. As a result, from the microstructural observations, a good bonding along the interface of the bonded couples and the interface is free from voids and microcracks.

AISI 1020 celigi genellikle civata, somun, makine govdesi ve parcalari, mermi kasasi ve konstruksiyon celigi olarak kullanilmaktadir. Bu calismada, AISI 1020 celigine 1560 ppm bor ilave edilmistir. Dokum islemi sonrasi borsuz ve 1560 ppm borlu celikler haddelenmistir. Haddeleme sonrasi 980 oC’de 30 dakika isitildiktan sonra buzlu su, normal su, yag, oda sicakligi ve firin ortamlarinda sogutulmustur. Isil isleme tabi tutulan numuneler optik mikroskop ile incelenmis ve mikrosertlik olcumleri yapilmistir. Elde edilen sonuclar literatur ile karsilastirilarak tartisilmistir.

In this study, the superplasticity of a hypoeutectoid carbon steel with 0.7% C was investigated considering Al and Si contents. The hot-tension experiments (superplasticity experiments) were carried out at 650 and 730 °C with the deformation rates between 3.3×10−4 and 1.3×10−2 s−1. The results showed that the best superplasticity elongation of 290% was achieved with the specimen containing 0.6% Si. The maximum m-values were determined as 0.29 at the test temperature of 650 °C and in the deformation rate range of 1×10−3 to 1.3×10−2 s−1 in the specimen with 0.6% Si content and 0.53 at the test temperature of 730 °C and the deformation rate range of 1×10−3 to 1.3×10−2 s−1 in the specimen with 0.15% Al content.

Objective: To report the first case of a bilateral renal solitary fibrous tumor (SFT) as a metastasis of an inguinal malignant SFT. Clinical Presentation and Intervention: A 60-year-old male patient with a history of a right inguinal 7 × 8 cm soft tissue mass excision 9 years ago was referred to our clinic with abdominal pain. Both physical examination and chest X-ray were normal. Computed tomography revealed bilateral renal tumor. He was successfully treated with left partial and right radical nephrectomy. Histopathological examination showed a metastasis of the previous inguinal SFT. Conclusion: This case showed that although malignant SFT is extremely rare in the urogenital tract, this tumor should be included in the differential diagnosis when identified in the kidneys.

In this study, porous Ni–Ti and Co–Cr–Mo alloy couple was fabricated by powder metallurgy (PM) process. With this aim, Ni–Ti and Co–Cr–Mo alloys powder was compacted into the mould one by one with Co–Cr–Mo being the one side and Ni–Ti the other side. Then, Ni–Ti side of the specimen was synthesised by self-propagating high temperature synthesis (SHS) process. At the end of the SHS process (after the SHS process), the porous Ni–Ti alloy has occurred. Finally, the specimen was sintered at 1050°C into argon atmosphere. Scanning electron microscope with energy dispersive X-ray spectroscopy and X-ray diffractometer were used to characterise the microstructure and composition. It was seen from the results that porous Ni–Ti and Co–Cr–Mo alloy couple was successfully fabricated by PM process.

Thermal reactive diffusion (TRD) coating on a DIN 1.2367 die steel substrate was performed in a powder mixture consisting of ferrovanadium, ferrochromium, ammonium chloride, alumina, and naphthalene at temperatures of 1000, 1050, and 1100°C for 2–4 h. The carbide layers were characterized using the microstructure, microhardness, X-ray diffraction, and chemical analysis. Wear scars were analyzed on scanning electron microscopy (SEM) micrographs with an energy-dispersive X-ray spectroscopy module. Depending on the coating process time and temperature, the thicknesses of the vanadium carbide and the chromium carbide layers formed on the substrate were obtained in a range from 7 to 30 μm and 5 to 17 μm, respectively. The maximum hardness values of vanadium carbide and chromium carbide layers were measured as 2537 and 1973 HV, respectively. The test samples coated using the TRD method were analyzed with regard to abrasive wear behavior using three different loads (1, 2, and 3 N) and speeds of 40, 80, and 160 r...

In this study, 304 stainless steel was boronized using nano boron powders using a solid-state box boronizing technique. Boronizing processes were carried out at temperatures of 950 and 1000°C for 2 and 4 h of treatment. Nano boron was used as a source of boron and KBF4 salt was used as an activator. The boxes in which boron was processed were made of 304 stainless steel plates. A free-ball microabrasion test was performed on the boronized samples. Silicon carbide (SiC) abrasive powders (5 μm) were used in the abrasion experiments. The ball rotational speed was 73.7, 102.5, and 147.4 rpm in the free-ball microabrasion test. Boronized steels showed an improvement in abrasive wear resistance. Microstructures and wear surfaces of the samples were inspected using scanning electron microscopy (SEM) and optical microscopy. It was observed from SEM and optical examinations that boronizing time and temperature had an important effect on the thickness of the boride layer on steel surfaces. The presence of boride fo...

Most of the nasal polyps arise from the lateral walls of the nasal cavity. Nasal polyps originating from the nasal septum with choanal extension are extremely rare. We report a case of large choanal polyp that arised from the posterosuperior aspect of the nasal septum, and extended down to the oropharynx. A 52-year-old woman presented with a two-year history of progressive nasal obstruction and snoring. Findings of anterior rhinoscopy were in normal limits. We think that the term "septochoanal polyp" which, as far as we know, has not been mentioned in the literature before, can be used for this rare lesion.

Objectives: This study was planned to evaluate whether possible changes in the hematological parameters and the biochemical markers can be used to detect obstruction-induced (strangulated) intestinal ischemia. Materials and Methods: Forty rats divided into five groups underwent the following procedures: Group 1 rats were treated with only laparotomy (sham-operated controls). To the strangulated hernia groups surgical induction of strangulated intestinal obstruction was performed. Tissue and blood samples were taken at 30 minutes (group 2), 2nd hour (group 3), 4th hour (group 4) and 6th hour (group 5) respectively, and then LDH, CPK, ALP, AST, ALT, D-dimer levels and blood cells counts were measured and histopathological examination was done. Results: Focal mucosal necrosis accompanied was confirmed by histological findings in the strangulated intestinal ischemia group after second hour. Serum D-dimer, ALT, ALP, CPK levels and neutrophil count became elevated at second hour, which was statistically significant. Conclusion: In patients with hernia, after reduction of the intestinal hernia, raised levels of serum D-dimer, ALT, ALP, CPK levels and neutrophil count may indicate the presence of a bowel ischemia. However, more comprehensive clinical studies are required to evaluate the potential survival benefit by using the laboratory tests as a marker and/or a useful diagnostic tool of the need for laparotomy. Amaç: Bu çalışmada obstrüksiyonun neden olduğu intestinal iskeminin tespiti için, hematolojik parametreler ve biyokimyasal göstergelerdeki değişikliklerin kullanılıp kullanılamayacağı araştırıldı. Gereçler ve Yöntemler: Beş gruba bölünen 40 adet sıçana şu yöntemler uygulandı: Grup 1'deki sıçanlara sadece laparotomi yapıldı, diğer strangüle herni gruplarına ise cerrahi olarak strangüle intestinal obstrüksiyon oluşturuldu. Doku ve kan örnekleri sırasıyla 30. dakikada (grup 2), 2. saatte (grup 3), 4. saatte (grup 4) ve 6. saatte (grup 5) alındı ve daha sonra LDH, CPK, ALP, AST, ALT, D-dimer seviyeleri, tam kan sayımı ölçüldü ve histopatolojik inceleme yapıldı. Bulgular: Eşlik eden fokal mukozal nekroz histolojik bulgularla strangüle intestinal iskemi grubunda 2. saatte gözlendi. Serum D-dimer, ALT, ALP, CPK seviyeleri ve nötrofil sayımı 2. saatte arttı ve istatistiksel olarak anlamlıydı. Sonuç: Fıtık hastalarında redüksiyon sonrasında artmış serum D-dimer, ALT, ALP, CPK seviyelerive nötrofil sayımı barsak iskemisinin bir göstergesi olabilir. Bununla birlikte laparatomi gereksiniminin göstergesi olabilecek testlerin potansiyel faydalarının değerlendirilmesi için daha geniş prospektif klinik çalışmalara ihtiyaç vardır., Amaç: Bu çalışmada obstrüksiyonun neden olduğu intestinal iskeminin tespiti için, hematolojik parametreler ve biyokimyasal göstergelerdeki değişikliklerin kullanılıp kullanılamayacağı araştırıldı. Gereçler ve Yöntemler: Beş gruba bölünen 40 adet sıçana şu yöntemler uygulandı: Grup 1'deki sıçanlara sadece laparotomi yapıldı, diğer strangüle herni gruplarına ise cerrahi olarak strangüle intestinal obstrüksiyon oluşturuldu. Doku ve kan örnekleri sırasıyla 30. dakikada (grup 2), 2. saatte (grup 3), 4. saatte (grup 4) ve 6. saatte (grup 5) alındı ve daha sonra LDH, CPK, ALP, AST, ALT, D-dimer seviyeleri, tam kan sayımı ölçüldü ve histopatolojik inceleme yapıldı. Bulgular: Eşlik eden fokal mukozal nekroz histolojik bulgularla strangüle intestinal iskemi grubunda 2. saatte gözlendi. Serum D-dimer, ALT, ALP, CPK seviyeleri ve nötrofil sayımı 2. saatte arttı ve istatistiksel olarak anlamlıydı. Sonuç: Fıtık hastalarında redüksiyon sonrasında artmış serum D-dimer, ALT, ALP, CPK seviyelerive nötrofil sayımı barsak iskemisinin bir göstergesi olabilir. Bununla birlikte laparatomi gereksiniminin göstergesi olabilecek testlerin potansiyel faydalarının değerlendirilmesi için daha geniş prospektif klinik çalışmalara ihtiyaç vardır.

Diffusion bonding of duplex stainless steel to medium carbon steel was carried out with different temperatures for sound bonds. in the bonding process, relatively intermediate temperatures such as 750, 800, 850 and 900 degrees C were used with a bonding time of 30 min. In this study, microstructural changes and mechanical properties in the interface region of duplex stainless steel and medium carbon steel couples were determined. The results showed that, in interface region, Cr(23)C(6) was formed on the stainless steel side, while ferrite formation was observed on the carbon steel side as a result of mutual diffusion of C and Cr. (C) 2009 Elsevier Inc. All rights reserved.

Objective: The aim of the study was to investigate the effects of different resuscitative fluids on the healing of intestinal anastomosis in a hemorrhagic-shock rat model. Materials and Methods: Closed-colony Wistar male rats (n = 40; 8 rats per group) were subjected to volume-controlled hemorrhagic shock, followed by a 30-min shock phase. The animals were then resuscitated with one of the following fluids (which also corresponds to their respective groups): lactated Ringer’s solution (LR), hydroxyethyl starch (HES), 7.5% hypertonic saline (HS) and autologous blood (AB). There was also a control group (CL), which did not experience hemorrhagic shock or receive any resuscitative fluids. All rats underwent laparotomy, segmental resection and anastomosis of the left colon. Five days later, a 2nd laparotomy was performed and the anastomotic bursting pressure was measured in vivo. Thereafter, the anastomosed segment was resected to measure the tissue hydroxyproline level and the grade of anastomotic fibrosis. Results: All experimental groups (LR, HES, HS and AB) exhibited lower anastomotic bursting pressures than the CL group; however, nointergroup differences achieved statistical significance. The mean tissue hydroxyproline level and fibrosis grade also were similar across all 5 groups. Conclusion: In traumatic hemorrhagic shock, anastomosis safety does not appear to be affected by the type of fluid used for resuscitation. Moreover, LR, HES and HS all seemed to reinforce healing as effectively as transfused blood.

To compare c-erbB2 (HER-2/Neu) immunohistochemical staining results obtained in 2 pathology departments and evaluate the reproducibility of staining and assessments.Ninety primary invasive ductal carcinoma cases constituted the material of this study. For concordant assessment, serial sections from the same tissue blocks were prepared in both Turkey and Greece and were sent to each other. Evaluation of c-erbB2 (HER-2/Neu) staining was done independently in 2 departments by experienced pathologists. Stained slides were evaluated semiquantitatively in Turkey and both semiquantitatively and automatically in Greece.There was complete agreement on staining density in 58 (64.4%) cases in both centers. In 15 cases there were major discordances in staining degrees, and in 17 cases there was a major discordance. Hypothetical treatment decisions based on these results showed that 82% of patients would have been handled the same way.Comparison of immunostaining patterns performed at 2 centers provided valuable data that may be used in the development of quality assurance policies. The present study showed the usefulness of multicenter comparative studies in initiating the development of guidelines.

Castleman’s disease is a benign and rare disease developing in lymph nodes. It is characterized by B-cell hyperproliferation and B-cells produce interleukin-6. This disease has two types; multicentric type often presents with fever, hepatomegaly, splenomegaly or lymphadenopathy, whereas unicentric type is diagnosed occasionally. Multicentric type is treated with combination chemotherapy regimens and unicentric type is treated with surgery and/or radiotherapy. In this article, a 29-year-old male patient with unicentric type, hyalen vascular Castleman’s disease with local recurrence after surgery and treated with radiotherapy is presented with management and related literature review.

Adequate lymph node evaluation is required for proper staging of colorectal cancer, and the number of lymph nodes examined is associated with survival. In this study, we aimed to evaluate the factors affecting the number of lymph nodes retrieved from specimens of patients operated for colorectal cancer. Medical records of 320 consecutive patients with colorectal cancer were evaluated retrospectively whom had curative resection between 2002 and 2007. Variables such as age, gender, tumor localization, depth of tumor invasion, number of lymph nodes retrieved, specimen length, stage and grade of disease, type of surgery, primary/recurrence diseasei¯ presence of preoperative chemo radiotherapy (CRT), surgeon, staff surgeon, pathologist, and staff pathologist were recorded and the results were evaluated statistically. Mean number of lymph nodes retrieved was 14.98 (0 to 129) and mean metastatic lymph node number was 2.37(0-25). Tumor localization, staging, primary/recurrence disease, length of specimen, type of operation, pathologist (resident pathologist), staff pathologist, staff surgeon, presence of CRT affected statistically significiant in terms of lymph nodes harvested (p