Microstructure and Mechanical properties development of ZA27 alloy through heat treatment

In this work, ZA-27 alloy was fabricated and solid solution treatment at 120, 240 and 360 °C for 1 hr., microstructure and physical properties of alloy were studied by X-ray diffraction, scanning electron microscopy. Results observed that the microstructure of ZA-27 alloy manufactured (as-cast) was composed of α, β, η and ε phases, then decomposed to β phase at 360 oC. The heat treatment of ZA-27 alloys influenced on microstructure, decreasing of strength and hardness, but also causes increasing of elongation. The wear rates of changes increase with increasing solid solution treatment

Wear Behaviour of ZA27/SiC/Graphite Composites under Lubricated Sliding Conditions

The composites samples based on ZA27 alloy were subjected to tribological tests and the observed results are presented in this paper. The samples (ZA27/5%SiC and ZA27/5%SiC/5%Gr) were obtained by compo-casting technique. Their wear behaviour was compared to the base alloy. The wear tests were done by using a block-on-disc tribometer under lubricated sliding conditions. Tribological investigation were conducted for three normal loads (40 N, 80 N, and 120 N), three sliding speeds (0.25 m/s, 0.5 m/s, and 1 m/s), and sliding distance of 1200 m. The tested materials were analysed by the scanning electronic microscope (SEM) and the energy dispersive spectrometry (EDS). The presence of oil lubricant improved the wear resistance and friction behaviour of both composites and base alloy. The tested composites show much higher wear resistance than the corresponding matrix material. It was established that the ZA27/5%SiC/5%Gr hybrid composite has best tribological properties.

Assessing the Performance of Nano Lubricant on Zinc Aluminium Alloy

In the field of tribology, Zinc Aluminium (ZA) alloys have been widely investigated for their superior wear characteristics. They were found to be suitable alternatives for bearing bronzes for the operating conditions of high mechanical load and moderate sliding speeds. Addition of nano-particles in the lubricating oil (base oil) to enhance the characteristics of the base oil is known as nano lubrication. In this study, sliding wear behaviour of ZA27 was investigated under dry, base oil and nano oil lubrication conditions, by varying load, sliding distance and sliding speed. With the base oil as SAE 40, nano graphite was added in two step method which was further used to identify the lubrication regime under different lubrication conditions. From the limited study of single melt samples, the results appear that the wear behaviour of ZA27 alloy improved under nano lubrication conditions with reduction in operating temperature. It could be observed from SEM images that the presence of nano-particles reduced scarring and wear, leading to enhancement in the tribological performance of ZA27 alloy.

Dry Sliding Wear Performance of ZA27/SiC/GraphiteComposites

The paper describes the wear performance of zinc-aluminium ZA27 alloy, reinforced with silicon-carbide (SiC) and graphite (Gr) particles. The compo-casting technique produced the composite samples. The tested samples were: ZA27 alloy, ZA27/5%SiC composite, and ZA27/5%SiC/3%Gr hybrid composite. A block-on-disc tribometer was used during wear tests under the dry sliding conditions by varying the normal loads and sliding speeds. The sliding distance was constant during tests. The microstructure of the worn surfaces of the tested materials was analysed using the scanning electronic microscope (SEM) and the energy dispersive spectrometry (EDS).

Microstructural and basic mechanical characteristics of ZA27 alloy-based nanocomposites synthesized by mechanical milling and compocasting

Particulate nanocomposites with the base of ZA27 alloy were synthesized using an innovative route, which includes mechanical milling and compocasting. Scrap from the matrix alloy and ceramic nanoreinforcements were mechanically milled using the ball-milling technique, which led to the formation of composite microparticles. The use of these particles in the compocasting process provided better wettability of ceramic nanoreinforcements in the semi-solid metal matrix, which resulted in a relatively good dispersion of the nanoreinforcements in nanocomposite castings. The presence of nanoreinforcements led to the grain refinement in the matrix of nanocomposites. The mechanical properties of the synthesized nanocomposites are improved and compared with the properties of the metal matrix. The observed increase in the hardness of nanocomposites with Al2O3 nanoreinforcements (20–30 nm) was 6.5% to 10.8%, while the yield strength of these nanocomposites has increased by 12.2% to 23.2%. The hardness and compressive yield strength of the nanocomposites with Al2O3 nanoparticles (100 nm) increased by 1.7% to 8.0% and 2.3% to 8.3%, respectively. The increase in hardness of the nanocomposites with SiC nanoparticles (50 nm) was 11.5% to 20.6%, while the increase in the yield strength was 15.6% to 24.5%. The greatest contribution to the overall strengthening in the synthesized nanocomposites is the result of increased dislocation density due to the difference in coefficients of thermal expansion for the matrix alloy and nanoreinforcements.