Synthesis and Characterization of Mechanical Properties of AA8014 + Si3N4/ ZrO2 Hybrid Composites by Stir Casting Process

Lightweight materials are extremely needed for the manufacturing of industrial parts and are used in aerospace, automobile body shops, biomedical instruments, etc. Aluminium alloy is one of the light-weight materials, and it fulfills the industrial demands based on their natural strength/stiffness, enhanced temperature permanence, superior wear, and corrosion resistance. This experimental work considered aluminium alloy (AA8014) with reinforced particles of silicon nitride (Si3N4) and zirconium dioxide (ZrO2) for preparing aluminium hybrid composites. Hybrid composites are prepared by a stir casting process involving different process parameters. L27 orthogonal array is used for optimizing the stir casting parameters with the assistance of the statistical Taguchi approach. Stir casting parameters are the percentage of reinforcement (4%, 6%, and 8%), stir speed (400 rpm, 500 rpm, and 600 rpm), stir time (20 min, 25 min, and 30 min), and molten temperature (700 oC, 800 oC, and 900 oC). Mechanical performance such as wear and microhardness of the hybrid composites is evaluated. Minimum wear and higher microhardness are encountered at a percentage of reinforcement = 6%, stir speed = 400 rpm, stir time = 30 min, and molten temperature = 900°C. In wear analysis, the percentage of reinforcement highly influences the wear properties (7.06% contribution). In microhardness analysis, molten temperature parameter is the extreme influencer (11.15% contribution).

A Brief Introduction on the Development of Ti-Based Metallic Glasses

Ti-based metallic glasses (MGs) possess high specific strength, low elastic modulus, high elasticity, high wear and corrosion resistance, and excellent biocompatibility, which make them highly attractive as lightweight high-strength materials as well as biomaterials. However, the glass forming ability (GFA) of Ti-based MGs, particularly those bearing no toxic, noble, or heavy metals, that is, Be, Pd, or Cu alike, largely sets back their wide applications for the restricted critical glass forming size of these Ti-based MGs. In this review, the outlines in developing Ti-based MGs are delineated in order to provide an overall view on the efforts ever made to fabricate bulk size Ti-based MGs. The state of the art in the knowledge on the GFA of Ti-based MGs is briefly introduced, and possible directions for fabricating bulk size toxic and noble element free Ti-based MGs are discussed.

Effects of Graphene on the Wear and Corrosion Resistance of Micro-Arc Oxidation Coating on a Titanium Alloy

In order to improve the wear and corrosion resistance of micro-arc oxidation (MAO) coating on a Ti-5Al-1V-1Sn-1Zr-0.8Mo alloy, 0–0.20 g/L graphene was added to the electrolyte to prepare micro-arc oxidation coating. The thickness, roughness, micro-morphology, and composition of the MAO coating were characterized, and the wear and corrosion resistance of the coating was tested and analyzed. The results show that with 0.05 g/L of graphene in the electrolyte, the roughness of the coating decreased from 56.76 μm to 31.81 μm. With the increase in the addition of graphene, the microstructure of the coating became more compact, the diameter of micro-holes and micro-cracks decreased, and the corrosion resistance of the coating improved. The wear tests showed that the mass loss of the coating at the early wear stage (0~100 revolutions) was greater than that at the later stage (100~250 revolutions), and the wear resistance of the coating obtained by the addition of 0.10 g/L of graphene was the highest. With 0.10 g/L of graphene, the adhesion force between the coating and the substrate alloy is the largest, reaching 57.1 N, which is 9.98 N higher than that without graphene. After salt spray corrosion for 480 h, the coating with graphene has better corrosion resistance than that of a graphene-free coating.

Increasing wear and corrosion resistance of steel products by combined laser thermomechanical treatment

A technique is presented for hardening metal products, in particular, the main tools (hammers) and cases of core drilling bits made of steel 30HGSA, using thermomechanical surface treatment according to a separate scheme. The method of combined laser thermomechanical hardening used in the study consists in the use of shot peening followed by laser heat treatment. Its use makes it possible to increase the operational properties of steel products, in particular, their wear and corrosion resistance. Based on the results of theoretical and experimental studies, the paper substantiates the features of dynamic surface plastic deformation for the analysis of impact during shot peening. The advantages of using laser hardening without surface melting are presented. Experimental research methods are proposed for determining the structural-phase composition, structure of the surface layer, hardness and microhardness of the hardened zones of steel 30HGSA. The range of rational modes of impact shot peening and thermal laser treatment has been determined. A device for testing samples for wear resistance has been developed. Methods of testing for wear and corrosion resistance of the surface of samples are proposed for assessing the tribological properties and contact interaction of materials under quasi-static and dynamic loading conditions. It is concluded that rational technological modes of hardening tools made of steel 30HGSA using combined laser thermomechanical treatment allow increasing the depth of the hardened layer by ~1.5 times compared to laser heat treatment. In addition, they provide the microhardness of the surface layer of ~5400 MPa, which is ~2.5 times higher than the microhardness of the base material