Effect of the SiC particle size on the dry sliding wear behavior of SiC and SiC–Gr-reinforced Al6061 composites

The effect of size of silicon carbide particles on the dry sliding wear properties of composites with three different sized SiC particles (19, 93, and 146 μm) has been studied. Wear behavior of Al6061/10 vol% SiC and Al6061/10 vol% SiC/5 vol% graphite composites processed by in situ powder metallurgy technique has been investigated using a pin-on-disk wear tester. The debris and wear surfaces of samples were identified using SEM. It was found that the porosity content and hardness of Al/10SiC composites decreased by 5 vol% graphite addition. The increased SiC particle size reduced the porosity, hardness, volume loss, and coefficient of friction of both types of composites. Moreover, the hybrid composites exhibited lower coefficient of friction and wear rates. The wear mechanism changed from mostly adhesive and micro-cutting in the Al/10SiC composite containing fine SiC particles to the prominently abrasive and delamination wear by increasing of SiC particle size. While the main wear mechanism for the unreinforced alloy was adhesive wear, all the hybrid composites were worn mainly by abrasion and delamination mechanisms.     

Laser surface coating of Mo–WC metal matrix composite on Ti6Al4V alloy

Laser surface alloying of Mo, WC and Mo–WC powders on the surface of Ti6Al4V alloys using a 2 kW Nd-YAG laser was performed. The dilution effect upon the microstructure, microhardness and wear resistance of the surface metal matrix composite (MMC) coating was investigated. With a constant thickness of pre-placed powder, the dilution levels of the alloyed layers were found to increase with the incident laser power. The fabricated surface MMC layer was metallurgically bonded to the Ti6Al4V substrate. The microhardness of the fabricated surface layer was found to be inversely proportional to the dilution level. The EDAX and XRD spectra results show that new intermetallic compounds and alloy phases were formed in the MMC layer. With the existence of Mo content in the pre-placed powder, the β-phase of Ti in the MMC coating can be retained at the quenching process. With increasing weight percentage content of WC particles in the Mo–WC pre-pasted powder, the microhardness and sliding wear resistance of the laser surface coating were increased by 87% and 150 times, respectively, as compared with the Ti6Al4V alloy. The surface friction of the laser-fabricated MMC coatings was also decreased as compared with the worn Ti6Al4V substrate.     

Evaluation of mechanical properties of 1060-Al reinforced with WC particles via warm accumulative roll bonding process

In the present study, aluminum metal matrix composites (AMMCs) reinforced with tungsten carbide (WC) particles are manufactured through warm accumulative roll bonding (ARB). The composite microstructure shows excellent WC particle distribution in the Al matrices, and no reaction between Al and WC is observed. Compared with the ARBed 1060-Al, the Al/WC composites show a higher number of dislocations, as suggested by the introduction of WC particles. The tensile, hardness, and wear properties of the Al/WC composites are determined. The introduction of 3 vol% WC particles to the Al matrix via the warm ARB process leads to significantly enhanced mechanical properties.     

Effects of high temperature treatment on microstructure and mechanical properties of laser-clad NiCrBSi/WC coatings on titanium alloy substrate

Laser-clad composite coatings on the Ti6Al4V substrate were heat-treated at 700, 800, and 900 °C for 1 h. The effects of post-heat treatment on the microstructure, microhardness, and fracture toughness of the coatings were investigated by scanning electron microscopy, X-ray diffractometry, energy dispersive spectroscopy, and optical microscopy. The wear resistance of the coatings was evaluated under dry reciprocating sliding friction at room temperature. The coatings mainly comprised some coarse gray blocky (W,Ti)C particles accompanied by the fine white WC particles, a large number of black TiC cellular/dendrites, and the matrix composed of NiTi and Ni₃Ti; some unknown rich Ni- and Ti-rich particles with sizes ranging from 10 nm to 50 nm were precipitated and uniformly distributed in the Ni₃Ti phase to form a thin granular layer after heat treatment at 700 °C. The granular layer spread from the edge toward the center of the Ni₃Ti phase with increasing temperature. A large number of fine equiaxed Cr₂₃C₆ particles with 0.2–0.5 μm sizes were observed around the edges of the NiTi supersaturated solid solution when the temperature was further increased to 900 °C. The microhardness and fracture toughness of the coatings were improved with increased temperature due to the dispersion-strengthening effect of the precipitates. Dominant wear mechanisms for all the coatings included abrasive and delamination wear. The post-heat treatment not only reduced wear volume and friction coefficient, but also decreased cracking susceptibility during sliding friction. Comparatively speaking, the heat-treated coating at 900 °C presented the most excellent wear resistance.     

陶瓷颗粒增强镍合金复合涂层冲蚀磨损的试验研究

以WC,ZrO₂,Cr₂O₃和Al₂O₃陶瓷颗粒为增强相,镍合金粉末为基体,运用等离子喷涂技术制备四种陶瓷/镍合金复合涂层。采用冲蚀磨损试验机和正交试验方法,进行陶瓷颗粒相浓度、磨粒粒度、冲蚀角和速度对陶瓷颗粒/镍合金复合涂层抗冲蚀磨损性能影响的试验研究。采用表面形状测量仪对陶瓷颗粒/镍合金复合涂层磨损表面形貌进行测量和分析。试验结果得到WC,ZrO₂,Cr₂O₃和Al₂O₃四种陶瓷颗粒/镍合金复合涂层冲蚀磨损率的经验关联式。     

Uniting Strength and Toughness of Al Matrix Composites with Coordinated Al3Ni and Al3Ti Reinforcements

Hybrid aluminum composites are fabricated in a novel manner to characteristically induce a layer‐wise aligned distribution of micro‐scale Al₃Ni and Al₃Ti intermetallic particles that are formed in situ within a ductile Al matrix. The simple and unique Rolling of Randomly Orientated Layer‐wise Materials (RROLM) manufacturing methodology enables microstructural tailoring of the intermetallic reinforcing particles to prescribe enhanced crack tip deflection caused by the complex interaction of local veins of reinforcement particles, in an effort to overshadow the classical loss of toughness in large‐particle reinforced composites. The complimentary reinforcements and their interface with the Al matrix are revealed to have a gradual transition zone that functions to maintain critical cohesion with the particles and the matrix, empowering the superior load transfer capability of the particles, and reducing microvoid penetration into the matrix. In situ three‐point bending observations combined with a local strain field analysis, demonstrate the distinctive crack deflection mechanisms exhibit by the composite. Deviating from the norm, this specialized particle reinforced composite exhibited both strengthening and toughening mechanisms simultaneously, over control samples. The investigated design strategy and model material will assist materials development toward light‐weight, stronger, and tougher particle reinforced Al matrix composites.     

Titanium diboride particle-reinforced aluminium with high wear resistance

A TiB₂ particle (61 vol%, 4 m mean size) reinforced aluminium fabricated by liquid-aluminium infiltration was subjected to unlubricated rolling wear and was found from the weight loss to be 1.5 times more wear resistant than 17-4 ph stainless steel, twice as wear resistant as 1020 steel, 7.5 times more wear resistant than 2024 aluminium, and 12.8 times more wear resistant than the aluminium matrix. This wear resistance is attributed to the lack of particle pull-out and the ability of the TiB₂ particles to protect the softer underlying matrix from abrasion. This composite was approximately three times more wear resistant than AlN particle (50 vol%)-reinforced aluminium. The greater wear resistance of Al/TiB₂ compared to Al/AlN is due to the slow wear of the TiB₂ particles and the AlN particle pull-out. A slight decline in tensile strength and no effect on the modulus was observed in Al/TiB₂ after heating at 300 or 600°C for 240 h. This high-temperature stability is attributed to the lack of reactivity between TiB₂ and the aluminium matrix.     

Dry wear properties of A356-SiC particle reinforced MMCs produced by two melting routes

SiC particle reinforced metal matrix composites (MMCs) were produced by a common liquid phase technique in two melting routes. In the first route, 5, 10, 15 and 20 vol% SiC reinforced A356-based MMCs were produced. In the second route, an Alcan A356 + 20 vol% SiC composite was diluted to obtain 5, 10, 15 and 20 vol% SiC MMCs. In both cases the average particle size was 12 μm. The composites that produced by two different routes were aimed to compare the dry wear resistance properties. A dry ball-on disk wear test was carried out for both groups of MMCs and their matrix materials. The tests were performed against a WC ball, 4.6 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40–60%. Sliding speed was chosen as 0.4 m/s and normal loads of 1, 2, 3 and 5 N were employed. The sliding distance was kept at 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. A complete wear microstructural characterization was carried out via scanning electron microscopy. The wear behaviors were recorded nearly similar for both groups of composites. Diluted samples showed lower friction coefficient values compared with the friction coefficient values of the vortex-produced composites. This was attributed poor bonding between matrix and particles in the vortex-produced composites associated with high porosities. But, in general, diluted Alcan composites showed slightly lower wear rate relationship with the particle volume percent and applied load when compared with vortex produced materials.     

Effects of Al2O3 particle reinforcement on the lubricated sliding wear behavior of ZA-27 alloy composites

The present investigation deals with the effect of Al₂O₃ particle reinforcement on the lubricated sliding behavior of ZA-27 alloy. The composites with 3, 5, and 10 wt% of Al₂O₃ particles were produced by the compocasting procedure. Tribological properties of alloy and composites were studied, using block-on-disk tribometer at different specific loads and sliding speeds. The test results revealed that composite specimens exhibited significantly lower wear rate, but higher coefficient of friction than the matrix alloy specimens in all the combinations of applied loads and sliding speeds. The improved antiwear characteristics of the composites were influenced by positive effects of higher frictional heating on compatibility of the composite phases and suppressing micro-cracking tendency. Due to that, effects of reinforcing hard particles were manifested through the reduced wear rate of composites, especially in conditions of higher load, lower sliding speeds and higher Al₂O₃ particle content. In present wear tests, the significant forming of mechanically mixed layers was not noticed, what is confirmed by the SEM microphotographs.     

Effect of copper addition on wear and corrosion behaviours of Mg2Si particle reinforced composites

The purpose of this study is to investigate the effect adding Cu has on the wear and corrosion properties of “in situ” Mg₂Si particle reinforced Al–12Si–20Mg matrix composites, produced with help of the nucleation and growth of the reinforcement from the source matrix, in order to overcome the disadvantages of composites produced by externally reinforcing ceramic particles. Composites known as Al–12Si–20Mg–XCu were produced by adding Cu, at the rate of 1%, 2%, and 4%, to the Al–12Si–20Mg alloy in order to achieve this purpose. The microstructural characterisation, hardness, wear and corrosion properties of composites, produced using the casting method, were analysed. Dry environment wear experiments for investigated alloys were conducted using a pin-on-disc type wear device under different loads and at different sliding distances. The change in weight loss of the solution containing 30 g/l NaCl + 10 ml/l HCl, and the tafel extrapolation method were used to analyse corrosion behaviour. Results of microstructural characterisation concluded that as the amount of Cu added to the Al–12Si–20Mg alloy increased, the size and volume of the Mg₂Si particle, formed within the matrix, decreased, and CuAl₂ intermetallics formed within the matrix. Results of wear experiments concluded that adding Cu developed wear resistance under small loads; however, reduced wear resistance under high loads. According to results of corrosion experiment, corrosion resistance increased with the addition of Cu.     

Studies on machinability of Al/Si<Subscript>p</Subscript> + SiC<Subscript>p</Subscript> composite materials

This paper presents the experimental results on the machinability of silicon and silicon carbide particles (SiC_p) reinforced aluminium matrix composites (Al/Si_p + SiC_p) during milling process using a carbide tool. The total volume fraction of the reinforcements is 65 vol%. The milling forces, flank wear of the tool and the machined surface quality of composites with different volume fraction of SiC_p were measured during experiments. The machined surfaces of composites were examined through SEM. The results showed that the flexural strength and Vickers hardness are improved when certain volume fraction of silicon particles are replaced by silicon carbide particles with the same volume fraction and particle size and the effect of SiC_p on machinability is optimal when 9 vol% silicon particles in Al/Si_p was replaced by silicon carbide particles with the same volume fraction and the same particle size. Cracks and pits were found on the machined surfaces of composites due to the intrinsic brittleness of silicon particles.     

Effects of particulate reinforcement and heat treatment on the hardness and wear properties of AA 2024-MoSi2 nanocomposites

In this study, nanocomposites of AA 2024 aluminum alloy matrix reinforced with different volume fractions of nanometric MoSi₂ intermetallic particles ranging from 0 to 5%, were produced using mechanical alloying technique. For comparison, samples without reinforcing particles and mechanical alloying and a sample with micrometric MoSi₂ particles were also synthesized. The prepared composite powders were consolidated by cold and hot pressing and then heat treated to solution and aged condition (T6). The effects of MoSi₂ particle size, volume fraction and also heat treatment on the hardness and wear properties of the composites were investigated using Brinell hardness and pin-on-disc wear tests. The results indicated that although T6 heat treatment increases the hardness of all samples compared to as hot-pressed (HP) condition, the age-hardenability (aging induced hardness improvement) decreases after mechanical alloying and with increasing MoSi₂ volume fraction due to the high dislocation density produced during mechanical alloying. With increasing the volume fraction of nano-sized MoSi₂ particles up to 3–4%, the hardness of the composites continuously increases and then declines most probably due to the particle agglomeration. The wear sliding test disclosed that the wear resistance of all specimens in T6 condition is higher than that of HP condition and increases with increasing MoSi₂ content. Scanning electron microscopic observation of the worn surfaces was conducted and the dominant wear mechanism was recognized as abrasive wear accompanied by some adhesive wear mechanism.     

Mikrostruktur‐Untersuchungen zum Schwingungsverschleißverhalten von Nickelkomposit‐ und Ni‐P‐Schichten

Microstructural and oscillating sliding wear studies of nickel composites and electroless Ni‐P layers In many industrial applications, oscillating sliding wear leads to serious damage of construction components. To avoid this, different layers of electroplated nickel and nickel composites as well as chemically deposited nickel phosphorus layers are used and/or tested. The performance of these layers under oscillating sliding wear was characterized. Additionally microstructure characterisations took place regarding grain size, particle content and distribution as well as concerning crystallization and development of tetragonal phase nickel phosphide. These results correlate well with the Martens hardness of the layers and contribute to understand the oscillating sliding wear characteristics of the examined layers. Heat treated Ni‐P layers achieve twice the hardness of nickel dispersion layers; however, fail under oscillating sliding stress by embrittlement, cracking and debonding. On the other hand dispersion‐hardening nano composites with TiO₂ clearly exhibit a more favourable tribological behaviour. A solid content of approx. 3 vol‐% leads to dispersion and fine grain hardening effects, which cause good protection against oscillating sliding wear; thereby the Ni‐matrix remains ductile. The incorporation of very hard particles (SiC) intensifies the oscillating sliding wear process due to the abrasive effect of the particles.     

Comparative analysis of wear behavior of garnet and fly ash reinforced Al7075 hybrid composite

Al7075 hybrid composites reinforced with varying weight percentage (0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%) of each of garnet and fly ash were fabricated and characterized for their comparative wear assessment. The sliding wear test was conducted on a reciprocating tribometer in dry medium under the working conditions of applied normal load (2 N, 4 N, 6 N, 8 N), sliding velocities (0.04 m/s, 0.08 m/s, 0.12 m/s, 0.16 m/s), sliding distance (20 m, 40 m, 60 m, 80 m) and working temperature (25 °C, 50 °C, 75 °C, 100 °C). The experiments were performed as per steady‐state condition and Taguchi (L₂₅) orthogonal array design to evaluate specific wear rate of the Al7075 hybrid composites. The finding of results indicated that the wear rate was decreased with the increase in the filler content in both the case of garnet and fly ash reinforced Al7075 hybrid composites. The results from Taguchi experiments suggested that the filler content and load were the most significant factors affecting wear behavior of composites while temperature and sliding distance are the least significant factors. Also, the garnet reinforced Al7075 hybrid composite indicated less specific wear rate as compared to that of fly ash reinforced Al7075 hybrid composite.     

Influence of B4C on the tribological and mechanical properties of Al 7075–B4C composites

In the present investigation, the influence of B₄C on the mechanical and Tribological behavior of Al 7075 composites is identified. Al 7075 particle reinforced composites were produced through casting, K₂TiF₆ added as the flux, to overcome the wetting problem between B₄C and liquid aluminium metal. The aluminium B₄C composites thus produced were subsequently subjected to T6 heat treatment. The samples of Al 7075 composites were tested for hardness, tensile, compression, flexural strengths and wear behavior. The test results showed increasing hardness of composites compared with the base alloy because of the presence of the increased ceramic phase. The wear resistance of the composites increased with increasing content of B₄C particles, and the wear rate was significantly less for the composite material compared to the matrix alloy. A mechanically mixed layer containing oxygen and iron was observed on the surface, and this acted as an effective insulation layer preventing metal to metal contact. The coefficient of friction decreased with increased B₄C content and reached its minimum at 10 vol% B₄C.     

Microstructure and abrasive wear behaviour of B<Subscript>4</Subscript>C particle reinforced 2014 Al matrix composites

In this study, the microstructure and abrasive wear properties of varying volume fraction of particles up to 12% B₄C particle reinforced 2014 aluminium alloy metal matrix composites produced by stircasting method was investigated. The density, porosity and hardness of composites were also examined. Wear behaviour of B₄C particle reinforced aluminium alloy composites was investigated by a block-on-disc abrasion test apparatus where the samples slid against the abrasive suspension mixture (contained 10 vol.% SiC particles and 90 vol.% oil) at room conditions. Wear tests performed under 92 N against the abrasive suspension mixture with a novel three body abrasive. For wear behaviour, the volume loss and specific rate of the samples have been measured and the effects of sliding time and the content of B₄C particles on the abrasive wear properties of the composites have been evaluated. The dominant wear mechanisms were identified using SEM. Microscopic observation of the microstructures revealed that dispersion of B₄C particles was generally uniform while increasing volume fraction led to agglomeration of the particles and porosity. The density of the composite decreased with increasing reinforcement volume fraction but the porosity and hardness increased with increasing particle content. Moreover, the specific wear rate of composite decreased with increasing particle volume fraction. The wear resistance of the composite was found to be considerably higher than that of the matrix alloy and increased with increasing particle content.     

Erosion mechanisms of aluminium nitride ceramics at different impact angles

In this paper, erosion wear behaviour of aluminium nitride (AlN) ceramics is studied. The influence of particle hardness and shape on erosion of the AlN surface is examined. The effect of varying the impingement angle on the weight loss and the roughness parameters of AlN ceramics testing sample is also determined. Therefore, erosive wear behaviour of AlN ceramics was investigated using SiC and SiO₂ particles as erodents, at following impact angles: 30°, 45°, 60°, 75° and 90°. Scanning electron microscopy (SEM) was used to analyze the eroded surfaces in order to determine erosion mechanisms. The roughness parameters (R_a, R_z and R_max), before and after erosion with SiO₂ and SiC particles at 30° and 90° angles of impingement, respectively, were determined using a profilometer. It was found that the impact angle is influencing the erosion wear of the AlN ceramics and maximum erosion takes place at impact angle of 90°. The results indicate that hard, angular SiC particles cause more damage than softer, more rounded SiO₂ particles.     

TiCp/Ti6Al4V复合材料的耐磨性及磨损机制

为表征颗粒增强钛基复合材料在恶劣的磨粒磨损条件下的磨损行为,对熔铸法制备的TiCP/Ti6Al4V进行了磨粒磨损条件下的耐磨性试验,并利用SEM、EDX等技术分析了复合材料的磨损过程及磨损机制.研究表明:TiCP/Ti6Al4V复合材料的抗磨粒磨损性能,总体上随TiC颗粒体积分数的增加而提高,载荷越大、磨损时间越长,复合材料越容易表现出优异的耐磨性能;TiC的形态影响着耐磨性的提高,细小颗粒状或羽毛状TiC单位体积增加对耐磨性的贡献,比枝晶状TiC单位体积增加对耐磨性的贡献大约3.5倍;复合材料在磨损初始阶段,其磨损机制以形成犁削和磨沟为主,形成一次磨屑,随着增强相含量的提高,一次磨屑逐步减少,磨损以犁沟和剥层磨损为主,需要磨粒的反复作用才能形成磨屑,因此,耐磨性得到提高.     

Solidification behaviour of ceramic particle reinforced Al-alloy matrices

Novel metal matrix composites have been produced by cast production route. TiC and WC ceramic reinforcing particles have been successfully introduced into Al 6060, Al 319, Al 356, Al–7Si–5Mg, Al–20Cu and Al 2007 alloys. Refined grain structure and various intermetallic phase formation have been observed. Particle–melt and particle–solidification front interactions, solidification sequence and particle–matrix interfacial characteristics have been examined by means of metallography, SEM examination and EDX analysis. Particle distribution, intermetallic phase formation and location and grain structure are discussed in terms of ceramic-melt wetting characteristics, alloying element interfacial segregation and particle–solidification front thermal behaviour.     

Ti particle-reinforced surface layers in Al: Effect of particle size on microstructure,hardness and wear

Two types of Ti particles are used in an ultrasonic impact peening (UIP) process to modify sub-surface layers of cp aluminium atomized, with an average size of approx. 20 μm and milled (0.3–0.5 μm). They are introduced into a zone of severe plastic deformation induced by UIP. The effect of Ti particles of different sizes on microstructure, phase composition, microhardness and wear resistance of sub-surface composite layers in aluminium is studied in this paper. The formed layers of a composite reinforced with smaller particles have a highly misoriented fine-grain microstructure of its matrix with a mean grain size of 200–400 nm, while reinforcement with larger particles results in relatively large Al grains (1–2 μm). XRD, SEM, EDX and TEM studies confirm significantly higher particle/matrix bonding in the former case due to formation of a Ti₃Al interlayer around Ti particles with rough surface caused by milling. Different microstructures determine hardness and wear resistance of reinforced aluminium layers: while higher magnitudes of microhardness are observed for both composites (when compared with those of annealed and UIP-treated aluminium), the wear resistance is improved only in the case of reinforcement with small particles.