On the Hardness and Elastic Modulus of Phases in SiC-Reinforced Al Composite: Role of La and Ce Addition

The use of silicon carbide particles (SiCp) as reinforcement in aluminium (Al)-based composites (Al/SiCp) can offer high hardness and high stiffness. The rare-earth elements like lanthanum (La) and cerium (Ce) and transition metals like nickel (Ni) and copper (Cu) were added into the matrix to form intermetallic phases; this is one way to improve the mechanical property of the composite at elevated temperatures. The α-Al15(Fe,Mn)3Si2, Al20(La,Ce)Ti2, and Al11(La,Ce)3, π-Al8FeMg3Si6 phases are formed. Nanoindentation was employed to measure the hardness and elastic modulus of the phases formed in the composite alloys. The rule of mixture was used to predict the modulus of the matrix alloys. The Halpin–Tsai model was applied to calculate the elastic modulus of the particle-reinforced composites. The transition metals (Ni and Cu) and rare-earth elements (La and Ce) determined a 5–15% increase of the elastic modulus of the matrix alloy. The SiC particles increased the elastic modulus of the matrix alloy by 10–15% in composite materials.

Mechanical characterization and fractography of 100 micron sized silicon carbide particles reinforced Al6061 alloy composites

In the current exploration, the impact of the 100 to 125 micron size addition of silicon carbide (SiC) on the mechanical performance of Al6061 alloy has been studied. The Al6061 alloy dispersed with 6, 9, and 12 wt.% of SiC particles were synthesized by a two-step stir cast route. Two-step addition of the preheated particles into the melt helps avoid the agglomeration of the particles, which further contributes to enhancing the properties of composites. The orchestrated composites were exposed to microstructural examines and mechanical properties evaluation. Microstructural portrayals of acquired examples were completed by SEM microscopy, EDS, and XRD patterns. The event of SiC particles were affirmed by the XRD patterns. The density of the Al6061-SiC composites was increased with the addition of high-density silicon carbide particles. The hardness, ultimate, and yield qualities of metal composites have been improved with the increase in the content of SiC support. The ductility of SiC reinforced composites decreased with hard ceramic particles' incorporation in the Al matrix alloy. Various fracture mechanisms were observed in the Al6061-SiC composites using SEM.

High Pressure Sintering of Silicon Carbide with Mg-Cr3C2 Composite Additive

Porous silicon carbide was sintered at 1300 °C/30 MPa for 2 h with 4 wt.% magnesium alloy and 4 wt.% chromium carbide composite additives. The sintered ceramic presented density of around 92% of the theoretical density. No new phase was observed after sintering. Mg segregates around chromium carbide particles in sintered ceramic. The silicon carbide particles were mainly bonded by melt magnesium alloy and chromium carbide diffused in solid state. The voids existed in the sintered ceramic, but much more fracture occurred in silicon carbide particles during bending due to high bonding strength of sintering necks. Some voids existed in the ceramic, which act as crack sources during fracture.

Modification of the Properties of Al2O3/TZ-3YS Thermal Barrier Coating by the Addition of Silicon Carbide Particles and Fructose

Al2O3/TZ-3YS coatings developed by suspension plasma spraying were studied in the present work. Mechanical and thermal characterization was realized to evaluate the suitability of thermal barrier coatings. In addition, SiC particle reinforcement was evaluated for its effect on the mechanical properties of the coating. The problem with SiC reinforcement is its high melting point that causes a large amount of unmolten material to be deposited on the coating. One possible solution followed in the present study consists of including fructose as an additive in order to modify the suspension characteristics. The results conclude that the use of fructose as an additive increases the mechanical and thermal properties (from 1.0 to 1.6 W/m·K), since the microstructure is modified, and results in a lower porosity (17%) compared to the SiC coating (25%).

Improving wear resistance of epoxy/SiC composite using a modified apparatus

A centrifugal mixing method was developed to disperse ceramic particles inside a thermosetting polymer. Horizontal centrifugal equipment was used to fabricate cylindrical rods from epoxy reinforced with silicon carbide particles. Silicon carbide particles (SiC) are used for the outer coating of epoxy to increase wear resistance. In the centrifugal mixing process, there are three important variables: rotational speed, ceramic percentage and, ceramic size which affect ceramic particle distribution. This paper aims to find the relationship between these variables and the distribution of ceramic particles then determine the optimum conditions to get maximum wear resistance and hardness. From the experiment and analysis, it can be concluded that when mixing speed was greater than 600 rpm, the possibility of air bubbles formation was increased especially for ultrafine particles. Otherwise, the maximum wear resistance and hardness values were found in ultrafine size SiC samples reinforced with 30 wt% which were mixed at a low speed of 300 rpm.