Abrasive Research Articles

Effect of heat treatment on the microstructure, mechanical properties and tribological behavior of Ti-45Nb alloy fabricated by laser powder bed fusion

To avoid stress-shielding effects between biomedical implants and human bones, low modulus heat-treated Ti-45Nb specimens fabricated by laser powder bed fusion (LPBF) after annealing heat treatment were studied in this study. The microstructure and mechanical properties of the specimens revealed that (i) the as-built specimen consisted mainly of the β-TiNb phase, and heat treatment did not affect the phase species, demonstrating the thermal stability of the LPBFed Ti-45Nb alloy. (ii) After heat treatment, all the specimens exhibited excellent yield strengths (over 1100 MPa), and low Young's moduli (approximately 80 GPa). (iii) The specimens exhibited excellent wear resistance with the main wear modes of abrasive and adhesive wear and low COF (0.353-0.394) under a load of 20 N.

Effects of Al variations on the microstructure and mechanical properties of laser-cladding AlxNbMo0.5Ti1.5Ta0.5Cr0.5 refractory high-entropy alloy coatings

Lightweight refractory high-entropy alloy coatings (RHEAcs) of AlXNbMo0.5Ti1.5Ta0.5Cr0.5 (where x = 0, 0.1, 0.2, and 0.3) were fabricated on 316L stainless steel surface by pre-placed powder laser cladding (LC) technology. The incorporation of Al element significantly enhanced the forming quality of coatings, resulting in nearly defect-free coatings with a thickness of 1.2-1.4mm. Microstructural analysis revealed that the coatings were primarily composed of body-centered cubic (BCC) solid solution and C15-Laves phase. Due to the influence of a single brittle BCC phase, the Al-free coating exhibited high strength and brittleness, leading to numerous defects caused by thermal stress. The introduction of Al element refined the microstructure and facilitated the formation of Laves phases at grain boundaries, thereby alleviating stress to a certain extent. Consequently, the microhardness of the RHEAcs was significantly higher than that of the substrate, with the Al-free coating achieving the highest microhardness of 1250 HV, which was 5.89 times that of the substrate. Wear resistance results indicated that, prior to annealing, RHEAcs with varying Al content outperformed 316L stainless steel. Post-annealing, the coatings exhibited significantly lower friction coefficients compared with the annealed 316L substrate. The Al-free coating showed significant accumulation of abrasive particles, leading to severe abrasive and oxidative wear. Conversely, post-annealing oxidation induced the formation of dense and directional oxide accumulation, resulting in a notable improvement in wear resistance. Finally, the underlying strengthening mechanisms have been proposed and analyzed.

Wear behaviour of T4 and T6 heat treated LM28 composite reinforced with ZrO2 particles by stir casting method

Abstract The current study was performed to investigate the metal alloy LM28’s wear characteristics, strengthened by fine and coarse ZrO2 were investigated after undergoing thermal treatment with T4 and T6 process. Aluminium degasification tablets were used during the stir casting liquid metallurgy process to produce the composites with less porosity. ZrO2 was employed as fine (10–30 μm) and coarse (80–120 μm) particles in a step size of 3% from 0 to 12 wt%. The traditional T4 and T6 HT process was applied to the composite materials (LM28 nZrO2). T4 heat treatment involved in elevating the composites to 450 °C for 120–180 min before quenching them into the oil and age them naturally for 8–42 days at ambient room temperature. T6 HT was performed in a routine fashion, but also underwent artificial aging at 190–240 °C for 3–7 h before normal cooling. When compared to T4 HT process and non-HT composites, the hardness of T6 HT composites gives better results against wear property. The ideal level of hardness and resistance to wear of the composite was found in T6 HT composites when tested with a pin on a disk throughout a range of sliding distances and loads. Scanning electron microscopy demonstrated that T4 HT and non-HT composites suffered more surface damage than T6 HT composites when subjected to the same load and sliding distance. Initially, material was removed by an abrasive wear process, but this shifted to an adhesive one as sliding distance increased. T6 thermal treated composites are ideal for usage in tough conditions as a result of their excellent hardness and resilience to wear.

Enhancing microstructure, nanomechanical and tribological properties of TiAl alloy processed by spark plasma sintering with Si3N4 ceramic particulates addition

TiAl matrix composites reinforced with varying weight fractions of Si3N4 ceramic particles were successfully fabricated by the spark plasma sintering method. The microstructure, nanomechanical and tribological properties of the sintered composites were investigated. The microstructural characterization revealed the evolution of a quasi-continuous and continuous network structure consisting of minor fractions of in-situ formed Ti2AlN, unreacted Si3N4 ceramic particles and dominant Ti5Si3 intermetallic phases within the TiAl matrix at Si3N4 content above 1.5 wt%. The in-situ precipitated phases enhanced the nanomechanical and tribological properties of the composites. The 7Si3N4/TiAl composite displayed the best nanomechanical properties, including nanohardness, elastic modulus, and H/Er ratio among the sintered samples. The specific wear rate of the composites decreases with increasing reinforcement content. 7Si3N4/TiAl composite exhibited the lowest specific wear rate of 0.38 ± 0.55 10-4 mm3/Nm, representing a 95.6% improvement in wear resistance compared to the unreinforced pure TiAl alloy. The improved wear performance of the composites was attributed to their load-bearing capacity and wear resistance of the hard, in-situ Ti2AlN, Ti5Si3 and unreacted Si3N4 particles in the TiAl matrix. The composites displayed a transition from adhesive wear to predominantly abrasive wear where the hard Si3N4 particles prevented direct metal-to-metal contact and facilitated the formation of a protective tribolayer, resulting in enhanced wear resistance. Hence, the developed Si3N4/TiAl composites are suitable for various structural and tribological applications.

Tribological Behavior of Hybrid Aluminum-TiB2 Metal Matrix Composites for Brake Rotor Applications

This research investigates the feasibility of hybrid aluminum metal matrix composites (MMC) incorporating TiB2 particles for brake rotor applications. The composites were produced by incorporating both in-situ, submicron-sized TiB2 particles and regular micron-sized TiB2 powders via stir and squeeze casting techniques into a A206 aluminum alloy matrix. Systematic adjustments in the fractions of in-situ and ex-situ TiB2 particles were conducted to evaluate their impact on wear behavior and mechanisms. Combination of both particle types allowed composites with up to 10 vol% of reinforcements. Composites with higher proportions of ex-situ particles demonstrated increased wear resistance compared to those solely composed of in-situ particles, control specimens without TiB2, and conventional cast iron counterparts. The lowest wear rate for the hybrid composites sliding against phenolic brake pads was 1.1 x 10-5 mm3/Nm, signifying a 3-fold reduction relative to cast iron sliding against the same pads. Wear analysis elucidated distinctive mechanisms within the hybrid composites, characterized by mild fragmented abrasive wear, adhesive wear, and plastic deformation, accompanied by the formation of an intermixed tribo-oxide layer.

Combined hybrid machining of laser ablation-drilling small holes in Cf/SiC composites

Carbon fiber-reinforced silicon carbide composite material (Cf/SiC) serves as a typical advanced material for fabricating hot-end components of aircraft engines. Its unique properties, including high hardness and anisotropy, pose significant challenges in processing. Nevertheless, a crucial structural element of hot-end components, specifically the cooling and heat dissipation holes, necessitates hole machining within the Cf/SiC composites. The intricate nature of machining this material often leads to compromised surface quality and severe wear on cutting tools during the hole machining process. This study delves into the feasibility of combined hybrid machining of laser ablation-drilling(L-DCM) for fabricating small holes in woven Cf/SiC composites, along with elucidating the underlying material removal mechanisms. The findings reveal approach significantly enhances the cutting performance of hard alloys tools when dealing with ceramic matrix composites. Notably, the wear mechanisms of the cutting tools primarily involve abrasive wear and adhesive wear. The primary processing defects observed in the small holes include fiber pullout at the entrance and exit, as well as material delamination at the exit, which are primarily attributed to debonding at the layer interface and brittle fracture of the matrix. The subsequent drilling process, conducted based on laser drilling, effectively eliminates thermal defects such as the heat-affected zone and recast layer, as well as morphological defects like taper. Additionally, this approach mitigates the tool wear process, minimizes the impact of compression effects on material removal, and enhances the shear action of the tool. Consequently, the layer interface remains securely bonded and intact after processing, thereby preserving the material's strength.

Investigate the impact wear failure behavior of CoMoCr engine valve and valve seat pairs under harsh conditions

The wear of sealing face is one of the main reasons for the failure of engine valve and valve seat pair. Changes in engine combustion load, running time, temperature, and other operating conditions can affect the wear of valve-valve seat pair. In this work, the CoMoCr alloy cladding valves and valve seat were used as the pair, to investigate the influencing mechanism of combustion load and valve lift on wear. Three groups of tests under different combinations of combustion loads and valve lifts were completed on self-designed testing rig. The results demonstrate that the increase of combustion load and valve lift exacerbate the wear of the valve and valve seat, and valve lift has a more significant effect on wear than combustion load. The increased combustion load worsens the microslip process and intensifies the abrasive wear process. Whereas valve lift enhances the impact process, causing the dense tribofilm on the material surface to delaminate due to fatigue. Destruction of the tribofilm prevented effective protection of the underlying material, which increased wear process.

Corrosion and wear performance and mechanism study of ZrB2/AA6016

Abstract This study involved the fabrication of aluminum matrix composites reinforced with ZrB2/AA6016 particles using the KBF4-Al-K2ZrF6 reaction system， the composites were then subjected to T6 heat treatment. An investigation was conducted to examine the impact of varying friction speeds on the corrosion and wear characteristics of ZrB2/AA6016. An investigation was conducted to study the frictional wear behavior of ZrB2/AA6016 in the presence of 3.5wt. % NaCl, both before and after T6 heat treatment. The study also aimed to understand the underlying mechanism of this behavior. The results indicate that the T6 heat treatment mitigates the impact of thermal stresses and strains caused by thermal mismatch, hence enhancing the material's wear resistance. The coefficient of friction (COF) for heat-treated ZrB2/AA6016 is lower than that for unheated-treated ZrB2/AA6016. As friction increases, the pace at which the material wears down tends to decrease. At a friction wear velocity of 50 mm/s, the wear rate of the material is minimized both before and after heat treatment, measuring 0.23×10-2mm3/Nm and 0.22×10-2mm3/Nm, respectively. Through the utilization of XRD, SEM, EBSD, TEM, and XPS analytical techniques, it has been determined that the ZrB2 particles exhibit strong bonding with the Al matrix. Additionally, the particle diameters range from 50~150nm. Following the T6 heat treatment, the grain size measured 40.53μm, while the proportion of large-angle grain boundaries was found to be 66.4%. The accumulation of Cl- resulted in the formation of localized corrosion pits on the surface undergoing wear, hence hastening the deterioration of the material. The primary causes of wear failure are corrosive wear, abrasive wear, and oxidative wear.

Effect of Pulse Current on Friction Coefficient of 7075-T6 Aluminum Alloy and Microstructure Analysis

Abstract A study on friction is necessary to improve the forming quality of stamped parts. It has been found that pulsed current can improve the forming properties of aluminum alloys, mainly in terms of Joule heat and electroplasticity. Thus, this article revolves around the effect of different current densities on the friction and wear of 7075-T6 aluminum alloy sheets. The change rule of friction coefficient under different current densities is derived through a friction test, and the variable friction simulation model is established. Scanning electron microscope (SEM) and X-ray diffraction (XRD) are used to analyze the micromorphology and elemental composition of the wear surface. The diffraction peaks of Al are analyzed by XRD, and grain size and dislocation density are calculated. Finally, the actual stamping results are compared with the simulation results. The results show that the friction coefficient decreases with the increase of current density when the current density is less than 10 A/mm2, and the wear mechanism is mainly abrasive wear. When the current density is greater than 10 A/mm2, the friction coefficient increases with the increase of current density and the wear mechanism is mainly adhesive and electrical wear. The grain size and dislocation density mainly depend on the electrical plasticity. The variable friction model's simulated thickness distribution and rebound results align more with the situation.

Studies on Tribological Characteristics and Wear Mechanisms of (TiN + TiC) Hybrid Nanocomposite Claddings Deposited on TC4-Grade Titanium Alloy Substrate by the Tungsten Inert Gas Cladding Process

Abstract This investigation explored the viability of tribological properties enhancement with the deposition of TiC + TiN nanoparticulate-reinforced hybrid composite claddings in TC4-grade titanium alloy to meet the ever-increasing functional performance requirements employed under aggressive tribological environments. The composite claddings are processed by using the tungsten inert gas cladding process. The tribological performance of the hybrid composite cladding deposition was evaluated against the claddings with simplex reinforcement compositions such as TC4/TiC and TC4/TiN composite claddings and the substrate alloy. Initially, the formation and microstructural characteristics of the composite cladding depositions are studied based on the scanning electron microscope, X-ray diffraction, and energy dispersive spectroscopic analyses to confirm their successful formation. The average microhardness achieved with the deposition of composite claddings such as TiC/TC4, TiN/TC4, and (TiC + TiN)/TC4 is 936.25 HV0.2, 858.88 HV0.2, and 1116. 72 HV0.2, respectively, while the TC4 substrate alloy is about 332.38 HV0.2. The (TiC + TiN)/TC4 hybrid composite cladding composition has shown significantly increased surface hardness which is about 30% and 18%, respectively, compared with the TiC/TC4 and TiN/TC4 composite cladding compositions while about 235% enhancement compared with the TC4 substrate alloy. Compared with the TC4 substrate alloy, the wear resistance enhancement achieved with the deposition of TiC/TC4 and TiN/TC4 composite claddings is up to 22.62% and 38.92%, respectively, while with the (TiC + TiN)/TC4 hybrid composite claddings is up to 49.87%. Similarly, the average CoF of the TC4 substrate alloy, TiC/TC4, TiN/TC4, and (TiC + TiN)/TC4 composite claddings observed are 0.76, 0.49, 0.58, and 0.44, respectively, which indicates that 36%, 23%, and 43% are the enhancements achieved with the respective composite claddings. The SEM analysis of worn surfaces of the composite claddings reveals typical wear mechanisms such as adhesive, abrasive, oxidation, and delamination that are represented by various regions identified on the generated wear maps. The adhesive and delamination wear regions are relatively wider for the TiN/TC4 composite cladding than the TiC/TC4 composite cladding. The wear mechanism of the composite cladding with multiphase TiC and TiN reinforcement particulate has shown an increased prevalence of abrasive wear as a consequence the abrasive wear region is wider while decreasing the window for adhesive and delamination wear.

Evolution of tool wear and machining quality during dry milling of AlCoCrFeNi2.1 eutectic high entropy alloy

AlCoCrFeNi2.1, a new class of eutectic high entropy alloy (EHEA) has drawn significant interest owing to the lamellar structure of alternating face-centered cubic (FCC) and B2 phases. Properties such as high strength and high plasticity render the machining of this alloy challenging. Addressing this issue, the milling experiments were conducted under dry conditions to investigate the machining quality of AlCoCrFeNi2.1 EHEA as well as the tool wear. The cutting temperature and cutting force were measured to explain the changes in tool wear and machining quality. The tool wear mechanisms and evolution modes were clarified. Finally, the change of surface roughness and surface morphology under different parameters were analyzed and the characterization method of plastic flow marked by B2 phase was proposed. Results showed that both the cutting temperature and cutting force increase as the milling parameters become larger. The width of flank wear increases with the increase of the cutting speed and the feed rate when the volume of material removal volume is constant. The tool wear modes evolved differently with different cutting parameters, for instance, abrasive wear dominated while the cutting speed was less than 80 m/min, but for higher speeds up to 110 m/min, adhesive wear and coating peeling occurred. As the cutting speed increases further, crater wear on the rake face starts to arise in addition to the flank wear. Abrasive wear and adhesive wear with increasing feed rate were dominant until a certain threshold (0.10 mm/tooth) beyond which the coating peels off the tool. Furthermore, chipping occurred for a higher feed rate of 0.14 mm/tooth. In particular, the formation of tool adhesive wear is mainly caused by the FCC phase adheres. In terms of machining quality, larger cutting parameters will worsen the surface roughness and morphology as well as lead to deeper subsurface plastic flow. The research will be conducive to promoting the applications of AlCoCrFeNi2.1 HEA.

Influence of cryogenic treatment and tempering temperature on microstructural evolution and dry sliding wear behavior of AISI D3 cold-work tool steel

Abstract AISI D3 cold work steel was shallow and deep cryogenically treated and double tempered at 150, 250, and 350 °C temperatures. Cryogenic processes transformed the retained austenite into martensite, while double tempering produced Fe, Cr, and W-rich carbides. The wear losses of cryogenically treated specimens decreased by up to 60% compared to conventionally heat-treated samples. Worn surfaces mainly experienced abrasive and adhesive wear mechanisms. Due to the formation of homogeneously dispersed fine carbides at 250 °C, oxidative wear occurred at the matrix phase, resulting in the lowest wear rate. The samples tempered at 150 °C suffered from the severe abrasive action of hard carbide particles, while the samples treated at 350 °C failed because of carbide coarsening.

Digitized Seedbed Soil Quality Assessment from Worn and Edge Hardened Cultivator Sweeps.

Tillage tools for seedbed soil management are often subjected to low stress abrasion wear, which could negatively affect seedbed quality and crop productivity. Limited studies exist that quantify the effects of worn tillage tools on seedbed quality and crop yield. This research investigated the influence of tillage tool wear on seedbed preparation by evaluating the effect of cultivator sweep wear on soil tilth utilizing a light detection and ranging (LiDAR) sensor. The framework consists of a seedbed tillage field experiment using a Completely Randomized Design (CRD) experiment in six replicates of two-tillage treatments (new and worn cultivator sweeps). After seedbed tillage, loosely tilled soil aggregates were removed to expose the seedbed soil profile, and then seedbed roughness statistical measures were estimated from LiDAR-scanned seedbed soil surface. Three statistical analyses (Analysis of Variance (ANOVA), Kolmogorov-Smirnov (KS), and Earth Mover's Distance (EMD)) were compared to quantitatively evaluate the soil roughness estimated from the LiDAR seedbed surface data. Seedbed prepared by new and worn cultivator sweeps showed significant differences (p < 0.05) in soil roughness variables of standard deviation, coefficient of variation, and kurtosis. Data analysis from the ANOVA and KS methods revealed that LiDAR-extracted soil roughness patterns were statistically influenced by tillage treatment. EMD analysis detected noticeable disparities between the tillage treatments and new versus worn cultivator sweeps. This study concludes that tillage tool wear substantively affects seedbed quality, as evidenced by LiDAR soil profile estimated attributes of soil roughness and three statistical methods (ANOVA, KS, and EMD). Our study supports the adoption of LiDAR technology for seedbed management, highlighting its applicability to evaluate seedbed quality that accounts for the wear life cycle of cultivator sweeps.

Sustainable Grease Lubrication Induced by Graphene Oxide and LiFePO4

This study investigates the possibility of modifying lubricating greases by 2D graphene oxide (GO) and lithium iron phosphate (LiFePO4) to enhance their tribological performance. GO's layered structure plays a crucial role in reducing friction by facilitating easy sliding between rubbing surfaces, making it an effective solid lubricant. The impact of these additives on friction reduction, wear resistance, and the tribolayer formation ability is evaluated by ball‐on‐disc tribometry with an emphasis on durability and sustainability. Comparative results reveal that unmodified greases exhibit a high susceptibility to wear, including oxide formation and severe plastic deformation. In contrast, greases with GO show a notable reduction in friction, while the addition of LiFePO4 contributes to the formation of a continuous protective layer that substantially reduces abrasive wear. The combination of GO and LiFePO4 results in a homogeneous, durable tribofilm that effectively protects surfaces against severe wear providing long‐term friction stability. Although lab‐scale LiFePO4 is used, the findings suggest a great potential for extending the useful life of recycled LiFePO4 from lithium‐ion batteries, similar to commercial LiFePO4 thus confirming significant improvements in the grease performance but also highlighting the potential to advance toward more sustainable solutions in industrial applications and electric vehicles.

Hot isostatic pressing of ball milled novel grade high entropy alloys at different sintering time and the investigation of their mechanical and corrosion resistance properties

Abstract With the discovery of high entropy alloys, new materials with superior properties have emerged. According to recent research, high-entropy alloys’ multi-component structure and mixing entropy have made them more prominent than other alloys. Because of their excellent chemical and mechanical properties—such as high hardness, high-temperature resistance, high wear resistance, chemical stability, and high corrosion resistance—high entropy alloys outperform other material types in various applications. A new grade of mechanically alloyed high entropy alloy (HEA) of composition 23Fe-21Cr-18Ni-20Ti-18Mn was consolidated by a hot isostatic pressing (HIP) at a temperature of 1000 °C, at different sintering time of 30, 60, and 90 min respectively. We have investigated the impact of sintering time on the microstructure, mechanical, corrosion, and wear-resistance properties. The x-ray diffraction (XRD) spectra of the 30 min HIPed HEA sample showed dominant s-FeCr phases and traces of γ-Fe, and the Ni-Ti phases. Whereas, the 90 min HIPed HEA samples showed more dominant Ni-Ti and traces of γ-Fe, and β-Mn phases. There is a phase transformation from BCC to HCP of consolidated HEA at increased holding time. The density of the samples increases from 5.882 to 6.327 g cm−3 and the porosity percentage decreases from 12.93 to 6.35% with the increase in the holding time. The Vickers microhardness value for 30, 60, and 90 min HIPed 23Fe-21Cr-18Ni-20Ti-18Mn HEA at 1000 °C was found to be 433, 513, and 793 HV respectively at an indentation load of 0.1 kgf. The consolidated HEA sample undergoes an abrasive and oxidative wear mechanism with ploughing and plastic deformation modes. The morphology of the wear debris was investigated using SEM. The 90 min sintered sample showed an excellent corrosion resistance due to the high rate of material densification and minimum surface flaws.

Wear performance of antibacterial dental composite with Salvadora persica extract and hydroxyapatite as fillers

AbstractThe characterization of S. persica (Salvadora persica) extract, which involved evaluating its antibacterial activity, demonstrated the extract's strong efficacy. Additionally, incorporating it into PMMA/HA showcased the composite's good antibacterial activity. The objective of this work is to evaluate how the incorporation of S. persica extract affects the wear resistance of the dental composite PMMA/HA, considering the critical importance of wear resistance in dental applications. The wear response of this biocomposite was tested against an Alumina ball using a pin‐on‐disc tribometer. Initially, the hydroxyapatite (HA) micro particles demonstrate a remarkable influence on wear behavior when incorporated at an optimal percentage (10%wt). This optimal inclusion rate not only significantly increases the wear rate but also instigates a shift in the wear mechanism, favoring abrasive wear while minimizing adhesive wear comparing to PMMA. The addition of the extract nanoparticles to the composite PMMA/HA decreases the wear rate except the composite containing 10 wt% of each filler. Additionally, it introduces adhesive wear, in addition to the existing fatigue and abrasion wear. Thus, the composite PMMA/HA could accommodate up to 10 wt% of the S. persica extract as the optimal percentage that provides antibacterial activity to this biocomposite without exhibiting a deterioration in wear performance.Highlights The evaluation of the effect of incorporating S. persica extract, which provides antibacterial activity, on the wear resistance of the PMMA/HA dental composite generally demonstrates a reduction in this property. The addition of S. persica extract introduces adhesive wear in addition to the fatigue and abrasion wear already present in the PMMA/HA composite. The composite PMMA/HA can accommodate up to 10 wt% of S. persica extract without compromising its wear performance.

Abrasive Wear Characteristics of 30MnB5 Steel for High-Speed Plough Tip of Agricultural Machinery in Southern Xinjiang Region

The high-speed plough tip is the core soil-touching component in southern Xinjiang field cultivation, but the interaction of the plough tip with the soil results in severe wear of the tip. The friction behaviour of sand and soil on plough tips was investigated with a homemade rotary abrasive wear tester in a one-factor multilevel test with three parameters: moisture content, velocity/rotational speed and friction distance. The objective was to study the friction behaviour of the sand soil and plough tip and analyse and characterise the wear amount, wear thickness and compressive stress distribution, three-dimensional wear morphology and microscopic wear morphology of the plough tips. The results show that with increasing speed, the wear amount changes more gently; with increasing soil water content, the soil adhesion force and lubricating water film increase so that the wear amount follows a second-order parabolic law; and with increasing friction distance, the wear amount gradually increases, and the wear rate also shows an upward trend when the plough tip is in the abrasive wear stage. The tip makes contact with the firmer soil with higher surface compressive stresses, causing the most wear. As the friction distance increases, sand particles become embedded in the contact surfaces, creating a groove effect along with spalling pits caused by fatigue wear. During the whole wear period, the groove effect is always accompanied by spalling pits appearing repeatedly. The analysis of the wear micromorphology of the plough tip shows that the number of flaking pits gradually decreases in the direction of soil movement, and the form of damage changes from impact wear to plough groove scratches. Abrasive wear interacts with corrosive wear to exacerbate plough tip wear.

Regulation of reinforced phases and its influence on the properties of (Ni2B+C)/Cu composite by heat and mechanical treatments

In this paper, (Ni2B+C)/Cu composites were prepared by hot pressing sintering (HP), and then heat treatment (HT) and multidirectional forging (MDF) were carried out to regulate the amount, size and distribution of reinforced phases. The evolution behavior of local structure and its effect on properties during heat treatment and multidirectional forging were studied. Results show that the Vickers hardness and electrical conductivity of (Ni2B+C)/Cu composite after solid solution, multidirectional forging, and aging treatment can reach 171.1 HV and 46.5 %IACS, respectively, which are increased by 55.3 % and 69.1 % compared with the as-sintered. The tensile strength can reach 355.1 MPa, and the facture elongation is increased to 5.2 % compared with the as-sintered (0.3 %), achieving a transition from brittle fracture to plastic fracture. In addition, the dry friction and wear mechanism of the composite is mainly abrasive wear, while the current-carrying friction and wear mechanism changes from abrasive wear to a coexistence of abrasive wear and oxidation wear. This work provides a new way to improve the properties of (Ni2B+C)/Cu composites.

Development of laser felling modes of gas-thermal coating

The use of copper and its alloys to create parts for metallurgical equipment is associated with an increase in abrasive wear and high-temperature corrosion. In this regard, there is a need to apply a protective coating. In particular, to prevent wear and premature chipping of the metal of copper tuyeres, the surface is hardened with a coating of zirconium dioxide stabilized with yttria oxide by thermal spraying in an air atmosphere. Due to the difference in the coefficient of thermal expansion of copper (at T = 300 K: 16.7 µm/m оС and at T = 750 K: 19.7 µm/m оС) and its low resistance to gas corrosion, the application of zirconium oxide (produced by a preapplied intermediate layer that plays a role in matching the coefficient of thermal expansion (CTE) between the copper base and the ceramic coating. In addition, the intermediate layer protects copper from gas corrosion. In this case, The use of copper and its alloys to create parts for metallurgical equipment is associated with an increase in abrasive wear and high-temperature corrosion. In this regard, there is a need to apply a protective coating. In particular, to prevent wear and premature chipping of the metal of copper tuyeres, the surface is hardened with a coating of zirconium dioxide stabilized with yttria oxide by thermal spraying in an air atmosphere. Due to the difference in the coefficient of thermal expansion of copper (at T = 300 K: 16.7 pm/m °G and at T = 750 K: 19.7 pm/m оG) and its low resistance to gas corrosion, the application of zirconium oxide (produced by a pre-applied intermediate layer that plays a role in matching the coefficient of thermal expansion (CTE) between the copper base and the ceramic coating. In addition, the intermediate layer protects copper from gas corrosion. In this case, nickel-based alloys were used as intermediate layers. The use of nickel as the basis of intermediate layers is due to the fact that copper and nickel form a continuous series of solid solutions, such as cupronickel or monel metal-like structures. This, in turn, assumes a smooth transition of thermophysical properties from copper to nickel alloy. To ensure increased adhesion of the transition layer to copper by increasing the area of mutual contact between copper and the sublayer (dagger penetration) and significantly increasing the homogeneity of the material of the intermediate layer made of a nickel alloy, laser melting of the intermediate sublayer (Ni–B–Si system) was used on a laser complex based on laser LS-5 with a power of 5 kW with a KUKA KR-60HA robot in an argon atmosphere. To test the modes, experiments were carried out on copper samples of a flat shape and a body of rotation. The optimal parameters for the process of melting flat samples were: processing speed 33 mm/s, power from 400 to 3900 W, focal length from 200 to 230 mm, pitch between tracks: 0.25, 0.5 and 1 mm. The optimal parameters for the process of melting rotating samples were: laser radiation power 400–450 W, processing step 0.125; 0.5, focal length from 200 to 210 mm.

PETG as an Alternative Material for the Production of Drone Spare Parts.

Material selection is the main challenge in the drone industry. In this study, hardness, abrasive wear, impact resistance, tensile strength, and durability (frost resistance and accelerated ageing) were identified as important characteristics of drone materials. The additive manufacturing technology was used to produce the drone leg specimens and prototype. The suitability of PETG as a primary filament material in the design of the drone leg was investigated. Nine series were printed with different raster lines (0.1, 0.2 and 0.3 mm) and infill densities (30, 60 and 90%). Printed specimens were annealed in salt and alabaster, as well as immersed in liquid nitrogen. Series with raster line-infill densities of 0.1-30, 0.3-30, 0.1-90 and 0.3-90 were identified as the most interesting ones. Thermally treated specimens had better mechanical and durability properties, and infill density was found to be the most important printing parameter. Specimen annealed in salt with a raster line of 0.1 mm and infill density of 90% had the best results. Since ABS is the most common material used for drone leg production, its properties were compared with the PETG specimen, which showed the best properties. The potential of PETG as an alternative material was proven, while the flexibility, productivity and suitability of the leg drone design were additionally confirmed.