Addition Of Silicon Carbide Particles Research Articles

Wear coefficient and reliability of sliding wear test procedure for high strength aluminium alloy and composite

This paper describes the results of dry sliding wear tests of aluminium alloy (Al–Zn–Mg–Cu) composite was examined under varying applied pressures (0.2–2.6 MPa) and sliding speeds of 0.52, 1.72, 3.35, 4.18 and 5.23 m/s. The wear behaviour was studied using pin-on-disc apparatus against heat-treated steel counter surface, giving emphasis on the parameters such as wear coefficient as a function of applied pressure for alloy and composite for various sliding velocities. Wear coefficient of the alloy was noted to be significantly higher than that of the composite and is suppressed further due to addition of silicon carbide particles and applied pressure. It is noted that the experimental values are in good agreement with the theoretically calculated value. The maximum deviation of experimental values from the theoretical ones is noted to be around 10–15%. This supports the reliability of the test procedures and reproducibility of the test data.

RETRACTED: Dry sliding wear behaviour of cast high strength aluminium alloy (Al–Zn–Mg) and hard particle composites

This paper describes the results of dry sliding wear tests of aluminium alloy (Al–Zn–Mg) and aluminium (Al–Zn–Mg)–10, 15 and 25 wt.% SiCp composite was examined under varying applied pressure (0.2 to 2.0 MPa) at a fixed sliding speed of 3.35 m/s. The sliding wear behaviour was studied using pin-on-disc apparatus against EN32 steel counter surface, giving emphasis on the parameters such as coefficient of friction, rise in temperature, wear and seizure resistance as a function of sliding distance and applied pressure. It was observed that the wear rate of the alloy was noted to be significantly higher than that of the composite and is suppressed further due to addition of silicon carbide particles. The temperature rise near the contacting surfaces and the coefficient of friction followed reversed trend. Detailed studies of wear surfaces and subsurface deformation have been carried out. The wear mechanism was studied through worn surfaces and microscopic examination of the developed wear tracks. The wear mechanism strongly dictated by the formation and stability of oxide layer, mechanically mixed layer (MML) and subsurface deformation and cracking. The overall results indicate that the aluminium alloy–silicon carbide particle composite could be considered as an excellent material where high strength and wear resistance are of prime importance.

Wear behavior of Al–Cu and Al–Cu/SiC components produced by powder metallurgy

In the present study, the dry sliding wear behavior of some powder metallurgy (P/M) Al–Mg–Cu alloys with different weight percentage of Cu (0, 1, 2, 3, 4, and 5 wt%) and corresponding metal matrix composites reinforced with 5 or 10 vol% silicon carbide particles (SiC) have been carried using pin-on-disk apparatus. The tested specimens were tested against hardened steel disk as a counter face at room conditions (∼20 °C and ∼50% relative humidity). The normal load was 40 N and sliding velocity of counter face disk was 150 rpm (0.393 m/s) and total testing time of 60 min, which corresponds to a distance of 1414 m. Generally, both hardness and wear resistance were enhanced by the addition of Cu and/or SiC to the Al-4 wt% Mg alloy. The formations of mechanically mixed layer (MML) as a result of material transfer from counter face disk to the samples and vice versa were observed in all tested specimens.

Compressive Behavior of Al2O3—SiC Ceramic Composite Foams Fabricated by Decomposition of Aluminum Sulfate Aqueous Solution

In recent years, a new class of ceramic foams with porosity levels up to 95% has been produced by the chemical method with aeration of a suspension containing foaming agents. The method of foamed suspensions has originated from the chemical reactions of water-soluble salts. In this study, sintered cellular ceramic composites with varying degrees of reticulation are prepared using coarse and fine silicon carbide (SiC) powder. A new process has been developed in order to produce SiC particles containing alumina (Al2 O3) foam by chemical route. An aqueous solution of aluminum sulfate and ammonium sulfate plus SiC particles is fired to prepare ceramic foams up to 1200°C in a ceramic crucible. During heating, the viscous suspension is foamed, sulfate ions are volatilized, and an Al 2O3—SiC composite cake is obtained. The resulting Al2O3 are in networking morphology with flaky struts whereas SiC particles are encapsulated in the flaky alumina. These 3D connections of the struts are responsible for macropores and Al2O3 and SiC grains within the struts are responsible for micropores. Thus, a ceramic composite foam containing bimodal pore distribution is obtained. After sintering at 1550°C, compression tests are applied for the ceramic composite foams. High compressive strength is achieved after post sintering. Both sintering temperature and addition of SiC particles increase the compressive strength of the foam. Both SEM image and XRD analyses are carried out to examine composite microstructures and properties.

Effect of Graphite and/or Silicon Carbide Particles Addition on the Hardness and Surface Roughness of Al-4 wt% Mg Alloy

In this study, the fabrication of Al-4 wt% Mg-graphite and/or silicon carbide (SiC) particulate composites is described. Composites of Al-4 wt% Mg alloy with different volume percentage values of graphite and/or SiC particles are prepared using the compocasting technique. In this technique, graphite particles and/or SiC particles are added into a semi-solid slurry during the stirring of the melt. A pitched blade stirrer is used to stir the reinforcement particles in the slurry. The slurry is then poured in a metallic mold to obtain the cast composites. The effect of the addition of graphite and/or SiC particles and porosity content on the Rockwell hardness and machinability is studied in the present work. The results show that the porosities increase with increase in particles content while Rockwell hardness decreases with increase of graphite particles. But SiC particles are found to increase the hardness of composites. Surface roughness improves with graphite content in the cast composite, and poor surface finish is obtained when SiC particles are added.

Wear behavior, microstructure, and dimensional stability of as-cast zinc-aluminum/SIC (metal matrix composites) alloys

The wear behaviors of five different zinc-aluminum (ZA)-based alloys containing silicon, copper, and 8 and 16 pct on volume of reinforcing silicon carbide (SiC) particles were analyzed. Hardness, dimensional stability, and wear tests were performed on these five alloy samples. Microstructural investigation and semiquantitative chemical analysis of the different alloying characteristics of the cast samples, the wear surface, and the wear debris were obtained by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDXA), and X-ray diffraction (XRD). The addition of Si, Cu, and SiC has a significant effect on the solidification process and final morphology of the alloys. The five cast alloys tested showed dimensional stability for a period of 1000 hours at 165°C±2.5°C. The wear tests were performed using a pin-on-disc apparatus under dry and lubricated conditions. Loads of 29.43 N (3 kg), 49.05 N (5 kg), and 78.48 N (8 kg) and a velocity of 250 rpm (2 m/s) were used. The results indicate that the wear rate of ZA alloys is strongly dependent on test load in a non-linear relationship and that the addition of SiC particles improved the wear properties of the matrix alloys. Under dry conditions, there was considerable loss of material, particularly in the nonreinforced alloys. In addition, the nonreinforced alloys presented substantial local plastic deformation and transfer of elements between the disc, the sample, and the debris. The amount of element transfer can be correlated with the elements presented. The proposed wear mechanisms are discussed.

Reactive Oxygen Species Measured from Suspensions of Polymorphonuclear Leukocytes after the Addition of Silicon Carbide Particles

A sample of silicon carbide (SiC) dust was collected from a factory manufacturing SiC abrasives, then tested in vitro to find out whether it could produce reactive oxygen species (ROS) after its addition to human polymorphonuclear leukocyte suspensions. We compared the results of milled and unmilled SiC with those obtained from quartz dust and asbestos fibres, which are known causes of severe pulmonary lesions. ROS production was measured with the chemiluminescence (CD technique. CL values obtained with our two forms of SiC (milled and unmilled) were approximately twice those measured in the controls (where no mineral particles were added), approximately 80% of the values found with asbestos fibres, and only 12.5% of the values measured with quartz. Iron traces were found on the surface of a small number of the particles tested, which could be as a result of contamination. These iron traces could help to explain our findings, since, together with the iron traces present in the culture medium, they could have triggered ROS generation in a Fenton-type reaction.