Papers by Author: Guo Ding Zhang

Abstract: Friction and wear properties of aluminum matrix composites are studied, including brake speed, brake pressure, and surface temperature etc. A conclusion can be drawn that SiC particle reinforced aluminum matrix composites are of stable friction coefficient, high thermal conductivity, and excellent wear-resistance. Hubs of motorcycle with brake rings of Al/SiC composites were manufactured and exhibited an excellent braking performance.

Abstract: Fretting friction and wear of aluminum alloy, 5 and 10 vol.% SiCp/Al and Ni3Alp/Al composites under 5×10-4 Pa and atmosphere was investigated. Wear mechanism in vacuum was compared to that in atmosphere at different applied loads. The coefficient of friction (COF) of the SiCp/Al composites was larger than aluminum and Ni3Alp/Al composites, however, incorporation of SiC particles into Al alloy increased the fretting wear resistance of Al alloys, especially in vacuum. It should be notices that the maximum wear depth was larger in vacuum under fretting wear, and the Ni3Alp/Al composites show low fretting wear resistance.

Abstract: The objective of the present paper is to study the wetting phenomenon and improving methods of Al/SiC interfaces. The work of adhesion and contact angle of this system was calculated theoretically from the physicochemical model. The effects of alloy elements such as Mg and the processing temperature on wettability were also investigated theoretically. Based on the theoretical calculation results, some effective methods to improve the wettability were presented.

Abstract: Compared to the conventional constructive materials, SiC particle reinforced aluminum matrix composites have lighter weight and higher specific modulus, and are applied in the structure framework of solar battery array for space station. According to the requests of the material properties for this framework, aluminum matrix composites are specially designed and manufactured, and then deformed into components of different shapes and sizes for various uses. The composite components were of compact structure and excellent mechanical properties, and had passed all the application tests for the framework. The application of aluminum matrix composites achieves a good result that not only the framework weight was greatly reduced but also the comprehensive properties of the framework were improved greatly. Aluminum matrix composites exhibit a great potential for further application into aerospace.

Abstract: The objective of the present paper is to study the wetting phenomenon of metal-ceramic interfaces. Two composite systems, i.e., SiCox/Al+xMg and Al2O3/Al+xMg were selected for calculation. The effects of alloy elements such as Mg and the processing temperature on wettability were investigated theoretically. The calculated wetting contact angles from the physicochemical model are approximately in agreement with experimental values.

Abstract: A hybrid reinforced composite based on magnesium alloy AZ60A reinforced with B4C particulates and SiC wisker, with volume percentage of 12% of each reinforcement respectively, was fabricated using pressured infiltration processing technique followed by hot extrusion. The microstructure of the composite and the fracture surface of tensile sample were investigated by optical microscopy and scanning electron microscopy (SEM). The results show a nearly uniform distribution of the reinforcements throughout the as-extruded magnesium matrix, and the SiC wiskers were observed with its longitudinal distributing along with the extrusion direction. Tensile experiment after extrusion revealed that the hybrid reinforcements significantly increase the elastic modulus and ultimate tensile strength of the composite material. The elastic modulus and the ultimate tensile were reached to 80.2GPa and 420 MPa, which were 100% and 34% higher than that of the matrix material. Moreover, numerical models (FEM) by an axisymmetric unit cell method were used to investigate the evolution of voids volume fraction in metal matrix during tensile process. The results show that the cracking is prone to form and grow near wisker than particulates.

Abstract: Discontinuously reinforced aluminum (DRA) composites are attractive for a large range of engineering applications because of its excellent wear-resistance, high thermal conductivity and light weight etc. In this paper, DRA composites were designed and fabricated especially for automotive application, and their properties were measured. Brake discs of DRA composites were manufactured and their braking performances were investigated, including brake velocity, brake pressure, brake torque, brake deceleration, brake time and surface temperature etc. The test results show DRA composites exhibit an excellent braking performance.

Abstract: Morph-genetic synthesis, a preparation method using bio-structures as templates for fabricating micro-cellular materials, has attracted a considerable interest in recent years. In this report, we summarize our obtained results on synthesizing oxides and carbides based on wood templates (for TiC and SiC) and cotton templates (for Al2O3, SnO2 and SiC), respectively. The final products are observed to be faithfully retaining the micro-morphologies of their original natural counterparts, with the template bodies absolutely or partially replaced by the chemically synthesized compounds. These results suggest a new and handy way to fabricate materials with various microstructures, with deliberately choosing desired bio-structures from billions of different species as templates. Moreover, results on Al infiltrated wood templates, as a composite system, are also presented.