Effect of alloying additives on impact-abrasive wear of manual arc welded hadfield steel hardfacings

The results of studying the impact-abrasive wear of manual arc welded Hadfield steel hardfacings and this steel alloyed with Cr, Ni, Mo, B, Cu, and Si, both without and with coarse-grained tungsten carbide reinforcement, are presented. It has been found that under conditions of impactless wear the presence of the hardening phase in the Hadfield steel increases its wear by 40% on average compared to the wear of the base and alloyed Hadfield steels. With an increase in the impact energy from 2.8 to 5.6 J, the wear of the reinforced Hadfield steels decreases and becomes comparable with the wear of the base and alloyed Hadfield steels. Under the conditions of erosion by coarse particles, layers of the Hadfield steel reinforced by tungsten carbide have slightly lower wear rate than unreinforced ones.     

WC颗粒增强铁基耐磨复合材料的研究现状

WC颗粒增强铁基耐磨复合材料可显著提高耐磨件的使用寿命,在工业生产中有广泛的应用。文中总结了WC颗粒种类、WC颗粒度、铁基体等对WC颗粒增强铁基复合材料耐磨性能的影响,并探讨了WC颗粒增强铁基复合材料的制备工艺。分析表明,控制WC颗粒在铁基体的溶解和扩散,使WC颗粒分布均匀并与基体牢固结合,可有效提高耐磨性能;针对不同服役条件需选择合适的复合材料体系和制备方法。     

Dry Sliding Friction and Wear Mechanism of TiC-TiB2 Particulate Locally Reinforced Mn-Steel Matrix Composite from a Cu-Ti-B4C System via a Self-Propagating High-Temperature Synthesis (SHS) Casting Route

An Mn-steel matrix composite locally reinforced with in situ TiC-TiB₂ ceramic particulates was successfully fabricated via a self-propagating high-temperature synthesis (SHS) casting route in a Cu-Ti-B₄C system with various Cu contents. The effect of the Cu content on wear behavior, wear surface, and wear mechanism of the composite was investigated against an AISI H13 mating disc in similar testing conditions at various applied loads and sliding velocities. Moreover, the phase identification and microstructure of the composite were examined. With the increase in Cu content, the wear resistance of the Mn-steel matrix composite decreases first and then increases. Impressively, the composite with 30 wt% Cu content has the highest wear resistance. The enhanced wear resistance can be attributed to the combination of size of ceramic particulates, number of pores, and strength of the interfacial bonding. The dominant wear mechanisms of the TiC-TiB₂ ceramic particulate–reinforced Mn-steel matrix are ploughing grooves and delamination wear associated with more abrasion and adhesion.     

Dry three-body abrasive wear behavior of WC reinforced iron matrix surface composites produced by V-EPC infiltration casting process

This paper fabricated tungsten carbide (WC) particles reinforced iron matrix surface composites on gray cast iron substrate using vacuum evaporative pattern casting (V-EPC) infiltration process, investigated dry three-body abrasive wear resistance of the composites containing different volume fractions of WC particles, comparing with a high chromium cast iron. The fabricated composites contained WC particles of 5, 10, 19, 27, 36, and 52 vol.%, respectively. The results in abrasive wear tests showed that, with the increase in the volume fraction of WC particles, the wear resistance of the composites first increased until reached the maximum when the volume fraction of WC was 27%, then decreased, and was 1.5–5.2 times higher than that of the high chromium cast iron. The changes of the wear resistance of the composites with the volume fraction of WC particles and the mode of material removal in dry three-body abrasive wear condition were analyzed.     

Effect of surface nanocrystallization on abrasive wear properties in Hadfield steel

A nanocrystalline surface layer was synthesized on a Hadfield steel by shot peening treatment. The microstructure evolvement of the surface layer of the shot peening treated sample was characterized by optical microscopy, X-ray diffraction and high-resolution transmission electron microscopy. It has been shown that the grain sizes in surface layer were decreased to 11.1-17.4 nm after 60 min shot peening duration. Surface hardness was also increased greatly. Two- and three-body abrasive wear experiments were carried out for work hardening and original specimens, separately. The results showed that the wear resistance of the nanocrystallized Hadfield steel has distinctly been improved in case of soft particles used as two-body wear abrasives or light impact load applied for impact abrasive wear.     

离心铸造铁基梯度功能复合材料

用离心铸造的方法获取碳化钨颗粒增强铁基复合材料，分析了复合材料的力学性能、微观组织结构及界面反应。结果表明：WCP／Fe-C复合材料表层厚度为18～25mm，WCP体积分数约70％，其冲击韧度ak达到5～6J／cm^2，复合材料表层和基体硬度分别达到63～65HRC和50～55HRC。WC颗粒能够被高温铁液局部溶解，甚至解体，使复合材料表层和基体不同程度合金化。     

WC基刀具材料微观结构及其加工损坏机理研究

利用热压烧结工艺成功制备了WC基复合陶瓷材料,通过扫描电镜对WC基纳米复合刀具材料的显微结构、断裂方式及裂纹扩展情况进行了观察与分析。材料中由于ZrO2和Al2O3纳米颗粒的加入,促使其断裂方式以穿晶断裂为主,并伴有沿晶断裂。同时,研究了材料中纳米颗粒ZrO2和Al2O3的形态及分布。发现ZrO2的均匀分布在一定程度上影响WC晶粒的形状。通过透射电镜对纳米复合陶瓷中WC-ZrO2、WC-Al2O3、Al2O3-ZrO2的界面进行了观察,发现材料中气孔等缺陷较少,材料各相间具有较高的接合强度。同时,利用制备的刀具对钛合金（Ti6Al4V）进行了切削试验,并对刀具磨损和破损机理进行了分析与探讨,发现刀具主要的损坏机理为粘结磨损和疲劳磨损。     

Sliding wear behavior of Fe-Al and Fe-Al/WC coatings prepared by high velocity arc spraying

A comparative study was carried out to investigate the microstructure and tribological behavior of Fe-Al and Fe-Al/WC iron aluminide based coatings against Si₃N₄ under dry sliding at room temperature using a pin-on-disc tribotester. The coatings were prepared by high velocity arc spraying (HVAS) and cored wires. The effect of normal load on friction coefficient and wear rate of the coatings was studied. The microstructure and the worn surfaces of the coatings were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscope (EDS). The results showed that, the main phases in both coatings were iron aluminide (Fe₃Al and FeAl) and α. WC/W₂C particles were embedded in the matrix of the composite coating. With adding WC hard particles, the Fe-Al/WC composite coating exhibited higher wear-resistance than Fe-Al coating. But the friction coefficient of both coatings showed little difference. As the load increased, the friction coefficient decreases slightly due to a rise of friction contact temperature and larger areas of oxide film formation on the worn surface, which act as a solid lubricant. Increasing load causes the maximum shear stress occurring at the deeper position below the surface, thereby aggravating the wear. The coating surface is subjected to alternately tensile stress and compression stress during sliding, and the predominant wear mechanism of the coatings appears to be delamination.     

Dry sliding wear properties of unhybrid and hybrid Al alloy based nanocomposites

Abstract

Nanosize B₄C and/or MoS₂ particles reinforced AA2219 alloy composites were prepared using the stir casting process. The wear properties were evaluated for several speed (3.14–5.65 m s^?1), load (10–50 N) and distance (0–2500 m) conditions. The nanoparticles dispersion, density, wear resistance, morphology of the worn surface and loose wear debris were discussed in detail. The wear resistance improvement results by nanoparticle addition correspond well with the hardness. Between the nanocomposites, hybrid composites show significantly higher wear resistance for all load, speed and sliding distance conditions. The better wear resistance is attributed to the matrix strengthening by nanoparticles and the lubricant-rich tribolayer controlled wear in the hybrid composites. The intensity of abrasive, oxidation and delamination wear mechanisms decide the wear rate at any particular wear testing condition.     

Effect of rare earth on microstructure and carbides in WC-Fe composite coating

WC-Fe composite coatings were prepared on IC45/080A47 steel substrates by argon arc cladding technique. Minute amounts of La were added into the coating, and the microstructure was investigated to find the relation to rare earth. Results show that RE does not change the categories of phases, and the main components remain α-Fe, Fe₃W₃C, WC and W₂C. However, the distribution of carbide particles is optimised. It reduces the agglomeration and bridging in the cladding layer's structure, makes the particles distribute homogeneously and restrains the dissolution of WC and the formation of fishbone shaped dendritic carbides. It promotes the formation of granular carbide and refines grains. It also reserves the WC particles in the composite coating and improves the average hardness and wear resistance.     

Synergism between corrosion and wear on CoCrMo−Al2O3 biocomposites in a physiological solution

The use of metal matrix composite structures in biomedical implants can be a solution for decreasing the amount of degradation products. Thus, the present work aims to investigate the synergism between corrosion and wear on CoCrMo matrix 10% (vol) Al₂O₃ particle reinforced composites in phosphate buffer solution (PBS) at body temperature. Corrosion behavior was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization. Tribocorrosion tests were performed under open circuit potential, as well as under cathodic and anodic potentiostatic conditions using a reciprocating ball-on-plate tribometer. Results suggest that the addition of Al₂O₃ particles did not create a significant effect on corrosion behavior of CoCrMo alloy, however, it increased the wear resistance and decreased the corrosion kinetics when sliding in PBS solution.     

Influence of Al2O3 reinforcement on the abrasive wear characteristic of Al2O3/PA1010 composite coatings

In the present study, the abrasive wear characteristics of Al₂O₃/PA1010 composite coatings were tested on the turnplate abrasive wear testing machine. Steel 45 (quenched and low-temperature tempered) was used as a reference material. The experimental results showed that when the Al₂O₃ particles have been treated with a silane coupling agent (γ-aminopropyl-triethoxysilane), the abrasive wear resistance of Al₂O₃/PA1010 composite coatings has a good linear relationship with the volume fraction of Al₂O₃ particles in Al₂O₃/PA1010 composite coatings and the linear correlation coefficient is 0.979. Under the experimental conditions, the size of Al₂O₃ particles (40.5-161.0 μm) has little influence on the abrasive wear resistance of Al₂O₃/PA1010 composite coatings. By treating the surface of Al₂O₃ particles with the silane coupling agent, the distribution of Al₂O₃ particles in PA1010 matrix is more homogeneous and the bonding state between Al₂O₃ particles and PA1010 matrix is better. Therefore, the Al₂O₃ particles make the Al₂O₃/PA1010 composite coatings have better abrasive wear resistance than PA1010 coating. The wear resistance of Al₂O₃/PA1010 composite coatings is about 45% compared with that of steel 45.     

Wear Behavior of Ceramic Powder and Solid Lubricant Cladding on Carbon Steel Surface

Thick composite coatings of carbides on a metal matrix are ideal for use in components that are subjected to severe abrasive wear. It is a metal matrix composite (MMC) that is reinforced by an appropriate ceramic phase, a solid lubricant coating to reduce friction and to protect the opposing surface. This study tested the wear behavior of a carbon steel surface after cladding by a gas tungsten arc welding (GTAW) method to enhance wear resistance. The microstructures, chemical compositions, and wear characteristics of the cladded surfaces were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The coating was uniform, continuous, and almost defect-free, and particles were evenly distributed throughout the cladding layer. The results of wear tests indicate that the friction coefficient of the TiC coating is lower than that of AISI 1020 carbon steel. Thus, the wear depth of the TiC coating is only one tenth of that exhibited by the AISI 1020 carbon steel. The experiments confirm that the cladding surfaces of TiC particles reduce the wear rate and friction.     

Interface Structure and Wear Behavior of Cr26 Ferrous Matrix Surface Composites Reinforced with CTCP

Using cast tungsten carbide particles (CTC_P) and reduced iron powders as raw materials, the porous ceramic preforms with honeycomb, strip, and layer structure, respectively, were prepared by loose sintering process; then, the CTC_P/Cr26 ferrous matrix composites were fabricated by casting infiltration process. The microstructure of the composites was analyzed by SEM, XRD, and EDS. The results show that a sintered shell forms as a result of the reaction of Fe and W₂C in the CTC_P during loose sintering process; the inner part of the shell around the CTC_p consists of WC and Fe₃W₃C phases, while the outer part between the particles is dominated by Fe₃W₃C. Therefore, the strength of preforms is enhanced because the particles are connected with each other by sintered shell. During casting infiltration process, a transition layer constituted by WC and Fe₃W₃C formed at the interface of CTC_p and the matrix due to the dissolution and precipitation of the sintered shell in the high-temperature liquid iron. The three-body abrasive wear behavior of the composites was investigated. The result shows the wear resistance of honeycomb structure composite is comparable to that of whole layer (WL) structure composite, which is three times of heat-treated Cr26. However, the honeycomb structure composite has higher performance/cost ratio owing to the lower CTC_p volume fraction and higher strength and toughness compared with the WL structure composite.     

Wear behavior of AA1060 reinforced with alumina under different loads

The wear behavior of samples of AA1060 aluminum matrix reinforced with 15 vol% of alumina particles in a range of loads between 4.9 and 91.2 N was determined using a pin-on-ring machine at a velocity of 2.7 m/s. The counterface was a carbon steel ring of 272 HB in hardness. Optical and electronic microscopy, X-ray energy analysis and hardness measurement were performed in order to characterize the worn samples. A mild wear mechanism is present for loads lower than 80 N and at larger loads the mechanisms change to a severe mode. In the mild wear regime a mechanically mixed layer (MML), with iron from the counterface and material of the composite, was formed. This MML was responsible of the wear resistance of the composite. Two mechanisms were observed as a way to increase the resistance of the MML; first hardening by mechanical alloying and strain hardening, and then an increase in thickness. At a larger load the conditions produced large instabilities which prevented the formation of a protective mechanically mixed layer.     

On the comparison of the abrasive wear behavior of aluminum alloyed and standard Hadfield steels

The abrasive wear behaviors of aluminum alloyed Hadfield steel at the high and low stress wear conditions were studied and compared with non-Al alloyed Hadfield steel. The wear tests were done with the pin on disc method using the abrasive wheel. The main parameters such as alloy compositions, normal load, sliding speed and sliding distance were evaluated. It is shown that at the low stress condition, the aluminum alloyed Hadfield steel has higher wear resistance than the non-Al alloyed Hadfield steel. But at the high stress wear conditions, the non-Al alloyed Hadfield steel is more resistant than the Al alloyed.     

Multivariable Modeling of Impact-Abrasion Wear Rates in Metal Matrix-Carbide Composite Materials

Carbide-matrix hardfacings reinforced with spherical and angular particles of different size and density have been investigated about correlation of their specific material parameters—especially matrix hardness and microstructure parameters—with the wear rates in continuous impact abrasion test (CIAT). For this study, 12 different hardfacings have been characterized by the quantitative metallographic method for determination of specific structural parameters, such as the mean carbide diameter, carbide area fraction, and a distribution parameter of inter-particle distances (L _IPD). Results showed the high influence of the matrix hardness on the CIAT wear resistance followed by effect of the mean particle size. The length of inter-particle distance (L _IPD) has exhibited stronger additional effect on CIAT wear rate than carbide area fraction, whereas particle form (spherical or angular) showed no significant differences.     

Coarse cemented WC particle ceramic-metal composite coatings produced by laser cladding

Coarse cemented WC particle (600–900 μm) ceramic-metal composite coatings with a thickness of 1.2–1.5 mm were cladded on 20Ni4Mo steel surfaces using a laser of power 2 kW, diameter 5 mm and traverse speed 4–20 mm s⁻¹. The weight fraction of WC particles was 67 wt%. Compared with the behaviour of cemented WC particles of the same size and ratio in atomic hydrogen welded coating (AHWCs), the WC particles in laser-cladded ceramic-metal coating (LCCCs) show a uniform distribution in the molten zone. The microhardness of WC particles in LCCCs is 13.7–16.2 GPa, and their sizes are almost unchanged, which indicates that little heat damage occurs during laser cladding. The abrasive wear results showed that LCCCs have superior wear resistance to AHWCs. The wear mechanisms for LCCCs and AHWCs are analysed and compared.     

In Situ NbC Particulate-Reinforced Iron Matrix Composite: Microstructure and Abrasive Wear Characteristics

An niobium carbide (NbC) particle-reinforced iron matrix composite was fabricated by compounding gray cast iron with niobium wires through an in situ technique comprised of an infiltration casting process and a subsequent heat treatment. The NbC particles in the reinforcement phase were synthesized in situ through the reaction between niobium from niobium wires and carbon from the graphite phases produced by the heat treatment in gray cast iron. The microstructure and wear-resistance of the bulk niobium particle-reinforced iron matrix composite was studied at different NbC particle volume fractions (8, 15, 22, and 28 vol%), by scanning electron microscope, X-ray diffraction, and a wear tester. The NbC particles were observed to form tiny cuboids and nearly spherical particles which were evenly distributed in the matrix. The particle size of the NbC reinforcement was about 0.3?C3.5???m. The relative wear resistance of the bulk composite increased with increasing NbC volume fraction, and the wear resistance of the composite was 5.9-fold higher than that of the gray cast iron under a 20N load and at a 28 vol% volume fraction. Wear performance of the composite at different NbC particle volume fraction values was also analyzed.     

Dry sliding friction and casing wear behavior of PCD reinforced WC matrix composites

The friction and casing wear properties of PCD reinforced WC matrix composites were investigated using a cylinder-on-ring wear-testing machine against N80 casing steel counterface under dry sliding conditions. The results indicate that the friction and casing wear rate of PCD reinforced WC matrix composites are the lowest among the materials. As the applied load and sliding speed steadily increase, the friction coefficients of PCD reinforced WC matrix composites decrease. In addition, the casing wear rates increase with increasing load, but decline with sliding velocity. The dominant wear mechanism of the PCD composite is the micro-cutting wear, accompanied by adhesive wear.