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Ni-Mn-based metamagnetic shape memory alloys (MSMAs) have excellent properties such as magnetic shape memory effect, giant magnetocaloric and barocaloric effects, magneto resistance, and exchange bias effects. These properties introduce them as potential novel materials for technological applications. Therefore, understanding and controlling the wear behavior of NiMn-based MSMAs is an important consideration for mechanical properties. In terms of technological applications, detailed tribological studies clarify the robustness in the harsh environment. In this study, we have performed the tribological behaviors of NiMnX (X = In and Sn) MSMAs. Additionally, the specified alloys are fabricated by two different methods to measure the effects of the fabrication method. The results showed that the wear testing and track depths are affected by fabrication methods, the contribution of X element, and wearing methods. The effect of the load is less significant for reciprocal sliding unlike to pin-on disk. For the pin-on disk, 5 N load presents a clear decrease by means of friction coefficient. Through the experiments, temperature changes from 24.3 to 48.6 °C. Microstructural evaluations highlighted that the alloys fabricated by induction furnace have lower width of wear track. Lastly, the NiMnSn alloy fabricated by using the arc melter comparatively has the widest wear track, 1303 µm.

Bu makalede, iyonkürenin F2 bölgesinde bazı kritik yükseklikler (390, 410, 450, 500, 550 ve 600 km) ve düşük enlemler için iyonküre plazmasında meydana gelen (ordinari, ekstraordinari ve kutuplanmış) dalgaların sönüm katsayılarının karelerinin büyüklüleri teorik olarak hesaplanmıştır. Ordinari ve ekstraordinari dalganın sönüm katsayılarının büyüklüğünün kareleri kabul edilen şartlar için elektron yoğunluğunun enlemle değişimi ile benzerlik göstermekte, kutuplanmış dalga ise farklı bir davranış sergilemektedir. Bu durum kutuplanmış dalganın çarpıcı bir şekilde manyetik alana bağımlılığın bir sonucu olabilir. Bunun yanında kutuplanmış dalganın sönüm katsaysının karesinin diğerlerinden daha büyük olduğundan göz önünde bulundurulan şartlar için daha fazla sönüme uğradığı söylenebilir.

The present study makes use of two distinct production methods. The first method involves producing 1010 steel-based materials containing SiC, MgO, H3BO3, and B4C (wt%10 - wt%30) with varying weights through powder metallurgy. This step was followed by hot pressing. In the second group, after all the chemicals were stirred, 20 ml of epoxy and epoxy hardener were added to the mixture. Then, the mixture was set aside to harden. XRD and SEM-EDS analyses were conducted on the mixture to observe the morphological impacts. Furthermore, friction coefficient values of the materials were also identified following wear tests under varying weights. The XRD analyses revealed the phase structures of Fe3C, SiC, MgO, H3BO3, B4C, and Fe2O3. As for the SEM-EDS analyses, they concluded the surface appearance of S60 and S55B20, the hot-pressed materials, dependent on liquid phase sintering. SEM of epoxy- based S60E20 and S55B20E20 revealed white spherical structures and a flat matrix structure with shallow surface holes. In the pin-on-disc wear experiment, the friction coefficient value was reduced with the addition of SiC, MgO, and H3BO3 (S60) to 1010 steel (S100). By adding various amounts of B4C, the friction coefficient was reduced even further, resulting in the improvement of wear properties.

In this study, Ti6Al4V / B4C Metal Matrix Composite (MMC) was produced using powder metallurgy (PM) method. All powder metal materials mixed by adding 5%, 10% and 15% B4C by weight to the Ti6Al4V matrix were subjected to hot pressing at 950 0C. Pin on disc dry wear test was performed to determine the wear resistance of composite materials produced in different compositions. As a result of the wear tests performed at 300 rpm sliding speed, 300 m sliding distance and three different loads of 5N, 10N, 15N, the effects of Ti6Al4V compound on B4C reinforced wear properties at different rates were investigated. It was determined that composite materials reinforced with B4C powder give better results than unreinforced Ti6Al4V and generally, as the amount of B4C powder increases, the friction coefficient values decrease and the wear resistance increases. In the wear test, it was observed that the friction coefficient of all materials decreased as the load increased. As a result of the changes in B4C reinforcement ratios, differences were observed in wear types and wear track depth. In the experimental studies, it was determined that the wear resistance changes directly with the B4C ratios reinforced by weight and the highest wear resistance is in composite materials with a B4C ratio of 15%.

This study sets out to investigate the effects of CNF on the microstructure, corrosion, and mechanical properties of a carbon nanofiber (CNF)-reinforced diamond cutting tool matrix. First, CNF was added to bronze (i.e. the matrix) at different ratios (0, 0.25, 0.50, 0.75, and 1.00 wt%). Hot pressing was selected as the preferred method of production as it allows producing a larger number of compact samples. Next, the manufactured samples' microstructure, hardness, density, transverse rupture strength (TRS), corrosion, and wear properties were analysed. Then, their microstructures and phase compositions were examined using optical microscopy and XRD. Their hardness was measured using a microhardness device. Their TRS values were calculated using a three-point bending test. Their fractured surfaces were examined using SEM-EDS. Wear properties were examined using the reciprocating wear test. Their corrosion behaviours were analysed using potentiodynamic measurements. Optical microscope images showed that CNF exhibited flocculation in several areas along the bronze matrix. The samples' hardness increased significantly with higher CNF ratios, whereas their relative densities dropped slightly. The TRS reached its maximum value at 0.25% CNF. Beyond that, a significant drop was observed in TRS. The higher the samples' CNF ratios were, the less corrosion resistance they got due to the microgalvanic effect. The results of wear test showed that as the samples' CNF ratios rose, their wear rates and their friction coefficients incrementally dropped.

WOS: 000483462700011, Waste utilization is an important alternative to reduce disposal costs, potential environmental pollution problems, decrement of natural resources and production costs. In this study, it is aimed to create a different usage area for the slag wastes that cause problems to the environment and factories. For this purpose, the usability of slags (blast furnace, ferrochromium and converter) as a reinforcement material in epoxy composites were investigated for tribological applications. Epoxy matrix composites were produced by adding 30% of reinforcements with 61 mu m size. The epoxy composites were tested against a stationary Al2O3 ball in a ball-on-disk tester under the loads of 10, 15 and 20 N, at a sliding distance of 300 m and a rotational speed of 300 rpm. Wear mechanisms were also investigated by Scanning Electron Microscopy. Mostly, the slag fillers showed higher wear resistance than the Al2O3 reinforced composites. Among the slag fillers, the blast furnace exhibited superior tribological performance. While Al2O3 and blast furnace slag reinforced composites showed plastic deformation due to fatigue, transverse cracks and displaced reinforcement particles were observed in ferrochromium slag and converter slag reinforced composites. Increasing the applied load caused acceleration in wear rate. Thermal conductivity was increased by particle addition, which contributed to the improvement of the wear performance. This study provided that industrial wastes can be used as reinforcement material in composites and thus a cleaner environment can be obtained. (C) 2019 Elsevier Ltd. All rights reserved.

WOS: 000469772600019, AISI D2 steel is the most commonly used cold-work tool steel in its grade. In this study, microstructural characterization and some mechanical properties of borided AISI D2 steel samples were investigated. The boriding treatment was carried out at 900 and 1000 degrees C for 3, 5 and 7 hours by using Ekabor 2 powder and a solid-state box boriding technique. Wear behavior of borided and non-borided steel were conducted by linear reciprocating wear test using an Al2O3 ball as the counterpart. The sliding distances and the sliding speed were remained constant at 250 m and 5 mm/s, respectively, with the loads of 10, 20 and 30 N (being applied). Microstructural characterization revealed homogeneous, dense and fine-grained structure which had predominant dual phase boride (FeB+Fe2B) layer with minor of Cr-B, Mo-B, V-B, Mn-B interstitial compounds being present as well. The thickness and hardness values of the boride layer were in the range of 46.23-126.8 mu m and 2005-2227 HV0.1, respectively, depending on the process conditions. The results showed that the wear resistance improved by up to 6.7 times in comparison with non-borided AISI D2 steel. Severe plastic deformation was the effective wear mechanism in non-borided AISI D2 steel. However for the samples which were borided at 900 and 1000 degrees C, delamination and polishing type of wear mechanisms were observed, respectively. Surface hardness and boride layer thickness had a great effect both on wear rate and wear mechanism.

WOS: 000450762200032, In the present study, the metallographic, mechanical and tribologic behaviors of AISI D2 steel specimens coated with TiC through the titanizing process were investigated. The titanizing treatment was performed at the temperatures of 900 degrees C, 1000 degrees C or 1100 degrees C for 1h, 2h or 3h using a solid-state box thermoreactive diffusion technique. In all cases, the predominant phase in the coating was TiC, but the mechanical properties of the coating varied with treatment condition. The wear resistance of the coated samples against a linear reciprocating Al2O3 ball improved as the hardness and thickness of the coating increased. The effective wear mechanism of samples that had been treated at 900 degrees C, 1000 degrees C and 1100 degrees C were severe plastic deformation, delamination and polishing type wear, respectively. The wear performance was affected by coating layer's thickness and uniformity as well as its surface hardness, elastic modulus and toughness.

WOS: 000437057900015, Externally cooled rolls of a steel plant were coated using three different surface modification techniques, namely titanizing, boronizing and borotitanizing. The grown coatings were examined using optical microscopy, scanning electron microscopy, microhardness measurements, X-ray diffraction and Raman analysis. Depending on the coating technique, a wide range of coating thicknesses and microhardness values were obtained; the highest microhardness was obtained in the titanized sample, while the greatest coating thickness was obtained in the borotitanized sample. Wear tests were performed on the untreated and coated specimens using a ball-on-disc wear tester under two different loads (1 N, 3 N) at three different temperatures (25 degrees C, 25 degrees C, 45 degrees C). The average friction coefficient values decreased at elevated temperatures, and increased under increased load. Temperature had a significant effect on the wear mechanism. At room temperature the effective wear mechanism was delamination, while at 25 degrees C and 45 degrees C oxidative wear was observed. All of the surface modification treatments improved the wear resistance. The highest wear resistance was observed in the borotitanized sample.

This study examines abrasive and adhesive wear behaviour of austenitic stainless steel and its TiC alloyed composite produced through powder metallurgy technique. Abrasive wear tests have been carried out using a pin on disc wear tester under loads of 10, 20 and 30 N. For adhesive wear tests, a block on ring wear tester has been used under loads of 20, 40, 60 and 80 N. A possible correlation between the hardness, microstructure and wear behaviour of the samples has been investigated. The abrasive wear tests have revealed that the highest rate of mass loss occurred in the austenitic matrix stainless steel sample; also, mass losses decreased with an increased rate of reinforcing material in the composite. In adhesive wear tests, interparticle spacing developed from severe wear and extreme plastic deformation under heavy loads; however, at low loads, oxidation type wear was shown to be dominant.

Using powder metallurgy, composites of austenitic stainless steel were produced along with unreinforced stainless steel mixed with titanium, cobalt and molybdenum particles. Wear resistance of the materials was measured by a two body pin on disc wear tester. SiC abrasive papers of 80 and 220 mesh sizes were used as abrasive media. Wear tests were performed under loads of 10, 20 and 30 N at room temperature. The abrasive wear measurements showed that the softer, unreinforced austenitic stainless steel exhibited higher mass loss than the composites. Furthermore, the abrasive wear resistance of the reinforced austenitic stainless steel composites increased with increasing FeTi, FeMo, or Co volume content. In addition, the wear rate against the 80 grade SiC abrasive paper increased more than against the 220 grade SiC abrasive paper.

Effect of ferrochromium slag, zeolite and combinations on physical, mechanical, thermal conductivity and microstructure properties of bricks was investigated. They were substituted to brick raw material. Semi-dry mixtures were compressed with 20 MPa. Samples were fired at rate of 5 °C/min until 900 °C for 2 h. Characterization of fired bricks, density, porosity, water absorption, weight loss, compressive and bending strength, thermal conductivity properties and microstructural and phase analysis of bricks were determined. Mechanical strengths of bricks were higher than 7 MPa. Thermal conductivity of samples decreases 42.3%. Results showed that bricks with zeolite and slag could be used as construction material.

Different types of ceramic powders were coated on the surface of middle carbon steel using a plasma method. Coated surfaces were tested experimentally with regard to their abrasive wear resistance. To evaluate test data obtained, an experimental design method, which is based on the Taguchi method, was used. By using the Taguchi method, influence of test parameters, such as normal load, abrasive grit size, and material on wear resistance of coatings by calculating signal-to-noise (S/N) ratio and analysis of variance (ANOVA), could be estimated. From analysis of test results, it was determined that load factor has the most effect on wear of coating.