Effect of dual size particle distribution on processing and properties of AZ91D/SiCp magnesium matrix composites prepared by rotation cylinder method

Abstract

Spiral fluidity and hardness and wear experiments were carried out to investigate the effect of dual size (5 and 50 μ m) SiC particle distributions on the fluidity, hardness, and wear resistance of Mg - 9.1Al - 0.7Zn (wt-%) alloy containing 10 vol.-% SiC particles, with the aim of tailoring properties to specific applications. Although a decrease in the fluidity of the composites is observed, as expected, in the presence of SiC particles, the fluidity of the composites with dual size particle distributions was in some instances better than that of composites containing the same volume fraction of single size particles. The hardness and wear resistance of the composites with dual size distributions were weakly dependent on the mixing ratio. In terms of complete molten processing and tailored mechanical properties, the optimum mixing ratio of 5 and 50 μm particles appears to be 1:2.     

Abrasive wear of FeCr (M7C3–M23C6) reinforced iron based metal matrix composites

Abstract

The effects of volume fraction, particle size, and sintered porosity of FeCr (M₇C₃–M₂₃C₆) particulates on the abrasive wear resistance of powder metallurgy (PM) Fe alloy metal matrix composites have been studied under different abrasive conditions. It was seen that the abrasive wear rate of the composites increased with an increase in the FeCr volume fraction in tests performed with 80 grade SiC abrasive paper, but it decreased for tests conducted with 220 grade SiC abrasive paper. Furthermore, the wear rates decreased with an increase in FeCr size for composites containing the same amount of FeCr. Hence it is deduced that Fe alloy composites reinforced with larger size FeCr particles are more effective against abrasive wear than those reinforced with smaller ones. At the same time the results show that the beneficial effects of hard FeCr particulates on wear resistance far outweighed the detrimental effects of sintered porosity in the PM metal matrix composites. In addition, the fabrication of composites containing soft particles such as graphite or copper favours a reduction in the coefficient of friction, and increases the matrix hardness of the composite. For this reason graphite and copper were used in the matrix in different amounts to test their effect on the wear resistance. Increase in graphite and copper volume fraction allowed the formation of additional phases, which had high hardness and wear resistance. It was also found that the wear rate of the composites decreased considerably with graphite and copper addition.     

Sliding wear behaviour of Al-Si-Cu composites reinforced with SiC particles

Abstract

The sliding wear behaviours of an unreinforced monolithic Al-Si-Cu alloy and SiC particles reinforced composites containing 5, 13, 38 and 50 vol.-% with diameters of 5.5, 11.5 and 57μm were investigated. The results showed that the wear resistance of the composites is much higher than the monolithic alloy, and the larger and the more SiC particles, the higher the enhancement of the wear resistance. Metallographic examinations revealed that the subsurface of worn composites was composed of both fragmented particles and deformed matrix alloy. The depth of the particle fracture zone in the subsurface varied in the range of 20-35 μm at a sliding distance of 1.8 km, while the plastic deformation zone of the worn subsurface on monolithic alloy was more than 100 μm. Scanning electron microanalyses of the worn surface, subsurface microstructure and debris suggested that the depth of the particle fracture zone became smaller as the diameter of SiC particles increased. Increasing the hardness and decreasing the applied wear stress changed the debris morphology from flake to very small lumps.     

Rotating cylinder manufacturing method and investment casting of SiCp/AZ91HP magnesium composites

Abstract

This paper describes the rotating cylinder method for manufacturing, and investment casting for forming, composite slurry. Microstructural features, such as SiC particle distribution and grain refinement of the as cast composites, were investigated. Also the effect of SiC particle fraction and size, and process parameters on the microstructure and the mechanical properties are discussed. Attempts were made to evaluate the thermal stability of oxides against molten AZ91HP magnesium alloy. The oxides examined included CaO, CaZrO₃, and silica bonded Al₂O₃ and zircon flour. Finally, the tensile properties, hardness, and wear resistance of the as cast composites were evaluated and the results are compared with those of the as cast alloy.     

Aging and wear resistant characterization of al-5Mg-X(Si, Cu, Ti)/SiCp composites produced by pressureless infiltration method

The effects of SiC particle size and alloy elements such as Si, Cu and Ti on the response to aging treatment and wear resistance in Al-5Mg-X(Si,Cu,Ti)/SiCp composites fabricated by pressureless infiltration method have been investigated by hardness tester, scanning electron microscope (SEM), X-ray diffractometer (XRD), differential scanning calorimetry (DSC) and wear tester. The Al-5Mg-0.3Si-0.1Cu-0.1Ti/SiC_P composites had better wear resistance property among Al-5Mg-X(Si,Cu)/SiC_P composites. The wear resistance property of all the composites was enhanced after aging at 170°C for 8 hrs due to precipitates of '(Mg₂Si) phase. The wear resistance property of the composite as-fabricated with 50 m size of SiC particle is superior to that of the composite as-fabricated with 100 m SiC size of particle. In Al-5%Mg alloy aged at 170°C for 8 hrs, the frictional seizure appeared more than abrading speed of 1.90 m/s, but in Al-5Mg-(Si,Cu,Ti)/SiC_P composites aged at 170°C for 8 hrs, the frictional seizure was not found at abrading speed ranging from 0.5 m/s to 4.3 m/s.     

Wear behaviour of aluminium matrix TiB2 composite prepared by in situ processing

Abstract

The wear behaviour and microstructure of aluminium and Al-12Si alloy (A413) matrix composites containing 1 and 5 vol.-%TiB₂ particles have been investigated. The composites were prepared by an in situ reactive slag technique. The wear surfaces and wear products were studied after reciprocating and rolling - sliding tests. Wear resistance increased with increasing particle content, and the Al-12Si composites were more wear resistant than those with Al matrixes. The wear mechanisms are briefly discussed.     

Properties of reactively cast aluminium–TiB2 alloys

Abstract

A salt base reactive casting process has been employed to produce A356 aluminium casting alloys containing fine dispersions of TiB₂. These have been compared with commercially available Duralcan A356 material with SiC particles which have also been incorporated by a casting technique. Structural, mechanical, and wear properties have been measured. These show that TiB₂ is extremely effective in enhancing modulus in addition to significantly reducing the coefficient of friction when used against an alloy steel plate. The wear rate of the alloy is found to be independent of particle type but is governed mainly by volume fraction, as is the load transition from mild to severe wear. However, the wear mechanisms for TiB₂ and SiC composites are different when the steel disc is taken into account and the wear debris examined. The plate is effectively machined by SiC, resulting in extensive damage of the mating plate. Alloy A356 with TiB₂ additions is made by reactive casting a simple alloy to process and is thereby a viable alternative to low cost Al–SiC cast composites.

MST/1854     

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.     

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.     

Abrasive wear of Al2O3-reinforced aluminium-based MMCs

The effects of volume fraction, Al₂O₃ particle size and effects of porosity in the composites on the abrasive wear resistance of compo-casting Al alloy MMCs have been studied for different abrasive conditions. It was seen that porosity in the composites is proportional to particle content. In addition, process variables like the stirring speed, and the position and diameter of the stirrer affect of the porosity content in a way similar to that observed for particle content. In addition, the abrasive wear rates of composites decreased more rapidly with increase in Al₂O₃ volume fraction in tests performed over 80 grade SiC abrasive paper than in tests conducted over 220 grade SiC abrasive paper. Furthermore, the wear rates decreased with increase in Al₂O₃ size for the composites containing the same amount of Al₂O₃. Hence, it is deduced that aluminium alloy composites reinforced with larger Al₂O₃ particles are more effective against abrasive wear than those reinforced with smaller Al₂O₃ particles. At the same time the results show that the beneficial effects of hard Al₂O₃ particles on wear resistance far surpassed that of the sintered porosity in the compocasting metal-matrix composites (MMCs). Nevertheless, the fabrication of composites containing soft particles such as graphite favors a reduction in the friction coefficient. For this reason graphite and copper were used in the matrix in different amounts to detect their effect on wear resistance. Finally, it was seen that wear rate of the composites decreased considerably with graphite additions.     

Wear characteristics of TiC reinforced cast iron composites Part 2 – Abrasive wear

Abstract

The presence of carbide particles in metal matrix composites improves abrasive wear resistance properties. Abrasive wear characteristics of TiC reinforced cast iron composites have been investigated. The TiC particle size and distribution influence the wear properties of the composites. TiC reinforced cast iron composites possess better wear resistance properties than those of chromium cast irons with and without nitrogen.     

Production and properties of SiCp-reinforced aluminium alloy composites

A vacuum infiltration process was developed to produce aluminium alloy composites containing various volume fractions of ceramic particles. The matrix composites of aluminium with 9.42 wt%Si and 0.36 wt%Mg containing up to 55 vol% SiCp were successfully infiltrated and the effect of infiltration temperature and volume fraction of particle on infiltration behaviour was investigated. In addition to aluminium powder, magnesium was used to improve the wetting of SiC particles by the molten aluminium alloy. The infiltration rate increased with increasing infiltration time, temperature and volume fraction of particle, but full infiltration appeared at the optimum process parameters for the various volumes of fraction composite compacts. In addition, the microstructure, hardness, density, porosity and wear resistance of the composites were also examined. It is observed that the distribution of SiC particles was uniform. The hardness and density of the composite increased with increasing reinforcement volume fraction and porosity decreased with increasing particle content. Moreover, the wear rate of the composite increased with increasing load and decreased with increasing particle content.     

Incorporation of new technique for processing of Al/SiCp composites based on evaporative pattern casting (EPC) method

Abstract

A336 Al matrix composites containing different volume fraction and mean mass particle size of SiC particles as the reinforcing phase were synthesised by evaporative pattern casting (EPC) route. The process consisted of fabricating of EPS/SiC_p composite pattern followed by EPC of A336 Al alloy. The EPS/SiC_p pattern was made by blending SiC particles with expandable polystyrene (EPS) beads and placing them in expanding mould heating with steam until EPS beads expand completely. Uniform distributed SiC particles around the EPS beads and locally movement of them during pouring and degradation leads to homogenous distribution of particles in final Al/SiC_p composite. Higher modulus, strength and hardness were observed in the composites than the unreinforced Al alloy part. The fracture surfaces of the composite samples exhibited dimple surfaces and fracture in SiC particles.     

Dry sliding wear of TiB2 particle reinforced aluminium alloy composites

Abstract

Al–4 wt-%Cu alloy and composites reinforced with 10 and 20 vol.-% of TiB₂ particles were prepared by powder metallurgy followed by hot isostatic pressing. The dry sliding wear behaviour of specimens of these materials was investigated. Pin-on-disc measurements showed that the wear resistance of Al–4Cu alloy can be improved dramatically by the addition of 20 vol.-%TiB₂ particles. This was due to the high hardness of the TiB₂ particles, and to strong particle–matrix bonding. The wear data were found to correlate with SEM observations.     

Investigation of corrosion and mechanical properties of Al–Cu–SiC–xNi composite alloys

In this study, dry sliding wear behavior and corrosion resistance of Al–Cu–SiC–xNi (x: 0, 0.5, 1, 1.5 wt.%) composites were investigated. Effect of nickel content on the microstructure and hardness of the alloys was also studied. Wear tests were conducted using a ball on disc wear test device. Corrosion behavior of Al–Cu–SiC–xNi composite alloys in 3.5% NaCl solution was investigated by using potentiodynamic polarization, impedance spectroscopy and cronoamperometric methods. The results showed that the hardness of the composite alloy increases with increasing nickel content. Maximum wear resistance is reported with the addition of 1 wt.%Ni. It was determined that corrosion resistance of Al–Cu–SiC composite alloys improved with increasing nickel content in the alloy.     

Quantitative evaluation on wear resistance of aluminum alloy composites densely packed with SiC particles

Abstract

Wear behaviour was investigated for high volume fraction SiC particulate reinforced aluminum alloy composites by considering the shear stress acting on the specimen and the wear debris formed during sliding wear. The SEM morphology of worn subsurfaces showed that particles are fragmented, mechanically mixed, and then aligned in the wear direction caused by normal and tangential stresses. Wear debris were initially tiny lumps but finally delaminated due to the shear stress. A theoretical wear model was proposed for plastically deformable specimens worn by a rigid non-deformable steel ring by analysing the interspacing of SiC particles and the tangential stress applied to the worn surface. Predictions of this theoretical wear model were in good agreement with experimental results.     

Wear behaviour of ZnAl27/TiCp metal matrix composites under sliding conditions

Abstract

The effect of TiC content on the wear resistance of a Zn–Al alloy was investigated under 300–900 N loads. Sliding tests were carried out to study the wear behaviour of TiC_p reinforced ZnAl27 metal matrix composites (MMCs) against AISI type 1050 steel in a block on ring apparatus. The ZnAl27/TiC_p MMCs, which were prepared by the addition of 5, 10, and 15 vol.-% TiC_p, were produced by powder metallurgy, and the size of particulates was varied at 80, 20, and 5 νm. The powders were uniaxially cold compacted by increasing the pressure up to 250 MPa. Wear tests were carried out in an incremental manner, i.e. 300 m per increment and 1800 m in total. The results of these tests were used to investigate the relationship between weight loss, microstructure, surface hardness, friction coefficient, particle size, and particulate percentage. It was observed that TiC_p particulate reinforcement is beneficial in increasing the wear resistance of ZnAl27 alloy, and TiC particulates in MMCs tend to reduce the extent of plastic deformation in the subsurface region of the matrix, thereby delaying the nucleation and propagation of subsurface microcracks.     

Dissolution precipitation mechanism of TiC/Ti composite layer produced by laser cladding

Abstract

TiC reinforced Ti matrix composite layer was fabricated by laser cladding of Ti and TiC powder mixture on Ti–6Al–4V alloy. Dissolution precipitation mechanism was speculated to illustrate the formation of TiC dendrite in the composite layer. Microstructure evolution of the composite layer has been explained by this mechanism. The composite incorporates the advantages of external particle composites and in situ synthesised particle composites. This mechanism offers an alternative novel idea for the design of bulk composites as well as composite layers. The composite layer exhibits high hardness and excellent wear resistance.     

Influence of the hard coated B4C particulates on wear resistance of Al–Cu alloys

In the present study, sliding wear tests were carried out on different sizes and volume fractions of coated B₄C particles reinforced 2024 aluminum alloy composites fabricated by a squeeze casting method. Microstructural examination showed that the B₄C distributions were generally homogeneous in the matrix while some particle clusterings were observed at relatively high particle containing composites. As compared to the 2024 Al matrix alloy, the hardness of the composites was found to be greater. It is observed that the wear resistance of the composites was significantly higher than that of the unreinforced aluminum alloy, and increased with increasing B₄C particles content and size. The hard B₄C particles act as a protrusion over the matrix, carries a major portion of the applied load and protect the abrasives from penetration into the specimen surface. Combination of rough and smooth regions is distinguished on the worn surface of the composites. The depth and number of grooves in composites decreased with increasing volume fraction of B₄C particles, and the worn surfaces of composites were relatively smooth.     

Investigation of the abrasive wear behaviour of ZA-27 alloy and CuSn10 bronze

In this study, abrasive wear behaviours of ZA-27 alloy and CuSn10 bronze were investigated using a purpose-built wear tester. The ZA-27 alloy was produced by permanent mould casting. The abrasive SiC particles having 63 μm grit size was added to the lubricant oil. The wear rate and friction coefficient of alloys were determined at the different test conditions such as sliding distance, applied load, linear velocity and percentage SiC weight content. The wear surfaces of alloys were examined using SEM and EDS analysis. The results showed that the wear rate of alloys decreased with the increasing of applied load and increased with the increasing linear velocity and abrasive SiC content. It was found that the SiC particle fracture was an important mechanism determining the friction and the wear rate of alloys. CuSn10 bronze showed higher wear resistance than ZA-27 alloy under abrasive test conditions except at high linear velocities.