Microstructure Exploration of the Aluminum-Tungsten Carbide Composite with different Manufacturing circumstances
In the last decade, as demand for high quality materials are increased, the development of lightweight aluminum (Al) also increased especially in aerospace and automotive industries. It has been well known that Al based metal matrix composites (MMCs) offers a very low thermal expansion coefficient, high specific strengths, wear and heat resistance as compared to conventional Al alloys. In order to combine all these properties, MMCs have become a very attractive method for various industrial applications. The interest in Tungsten Carbide (WC) as reinforcements for aluminum (Al) has been growing considerably. Efforts have been largely focused on investigating their contribution to the enhancement of the mechanical performance of the composites. The uniform dispersion of Tungsten Carbide in the Al matrix has been identified as being critical to the pursuit of enhanced properties. In this present research paper emphasis, the effect of Tungsten Carbide content on the Physical properties of the composites like SEM, XRD was investigated. The improvement of physical properties for composites of Al/WC has been compared with pure aluminum.
The mechanical and tribological characteristic of Aluminium-Titanium dioxide composites
The purpose of this work was to investigate the mechanical and tribological effects of Titanium dioxide (TiO2) reinforcement in Aluminium (Al). Aluminium composites consist of 99.8% pure aluminium reinforced with five different partions of TiO2. Aluminium powders were mixed with TiO2 by ball milling for 30 minutes in a planetary mixer. The powder mixture was compacted by the cold pressing technique at 250 MPa. Two different methods used for sintering. The green compact was sintered at 600 °C for 300 seconds in open atmosphere with an Ulta-High Frequency Induction System (UHFIS) and with furnace at 600 °C for 1800 seconds. The mechanical and microstructural properties of examples were compared for different amount of reinforcement. We have observed a maximum hardness for 5 wt.% TiO2 reinforced composites.
Effect of frictional heating on brake materials
Abstract An exploratory investigation was conducted concerning materials and their properties for use in aircraft brakes. The overall objective of the program is to develop improved brake materials primarily from a safety point of view. In this investigation a study was made in order to determine what improvements could be made in present brake materials. Primary consideration was given to the heat dissipation. Used brake pads and rotor disks, taken from aircraft at overhaul were analyzed to provide additional information on material behavior. A simplified analysis was conducted in order to determine the most significant factors which affect surface temperature. Where there are size and weight restrictions the specific heat and maintaining the contact area appear to be the most important factors. A criterion is suggested for determining the number and thickness of brake disks, within the limited space available in a wheel, to provide an optimal compromise between effective surface temperature of the disk and weight. This criterion is that the quantity ( αt max l 2 ) 1 2 should be approximately equal to 1 where α is the thermal diffusivity, t max is the time at the end of the braking cycle and l is half the disk thickness. For lower surface temperatures maximum benefit can be obtained by using materials of high specific heat (and density) and by maximizing the contact area.