The silicon carbide reinforced aluminum matrix composites (SiCp/Al) are widely used for its high specific stiffness and high specific strength. However, the poor surface quality and machined surface defects limit its further application. The aim of this paper is to investigate the effect of cutting parameters on the machined surface defects in high-speed milling of SiCp/Al composites. The tests were performed on a high precision computerized numerical control (CNC) precision milling machine using a polycrystalline diamond (PCD) tool, and the machined surfaces were measured by the scanning electron microscope (SEM).It was found that cutting parameters have a great influence on the depth of big pits. A high feed rate and a low cutting speed correspond with a big cutting force, and result in a large depth of big pits.

For the purpose of investigating the effect on surface micro-topography of cutting parameters in high speed milling of SiCp/Al Composites, the high speed milling experiments were performed .The machined surface was measured by Taylor Hobson roughness tester and OLS3000 Confocal Laser Scanning Microscope. The acquired surface data was dealt with the three-dimensional roughness method. The three-dimensional root-mean-square deviation of the surface Sq and two-dimensional root-mean-square deviation Rq were compared. The effects of cutting parameters on three-dimensional roughness parameter were also investigated. The results showed that both feed rate and depth of cut have a little effect on the value of three-dimensional roughness parameter，and the cutting speed is the main affecting factor.

This paper presents an experimental study in high speed milling of SiCp/Al composites. Machining tests were carried out on a high speed milling machine by using chemical vapour deposition (CVD) diamond coated tools. The surface micro-topography was tested by the OLS3000 Confocal Laser Scanning Microscope. The Gaussian filtering method and the least square fitting method were used to treat the measured results. Two methods are compared according to the effect on keeping important original surface’s character. The results showed that the least square fitting method is suitable due to its good accordance to the original surface’s character.

Research on preparation of nanoporous silica aerogels that using cheap silica sol as silica source, undering atmospheric drying. Using orthogonal test method study the different components how to influence the gel time and the aerogel density and obtaining the best ratio. Also study the different PH value how to influence the gel time, aerogel density and the micro-structure. The results showed that: in Silica Sol, ethanol and water system, the ratio of silica sol and alcohol has significantly affected on gel time and aerogel density, the best volume ratio is 1:3, PH from 2 to 5 aerogel density is about 0.32g/cm3, but the gel time decreases rapidly, PH from 5 to 7 aerogel density increases to 0.4g/cm3quickly, and gel time changes a little, SEM showed that the micro-structure of aerogel is the best when the PH is 5. The non-critical drying method of cheap preparation comes true.

This paper presents an experimental study in milling of SiCp/Al composites on a high precision machine by using chemical vapor deposition(CVD) diamond coated tools and polycrystalline diamond (PCD) tools. The tool wear was observed and measured by an optical microscope and a scanning electron microscope (SEM). The results show that the coating rupture causes the failure of the CVD diamond coated tools. The PCD tools’ wear is less. At the relatively low cutting speed, the wear pattern of PCD tools is the flank wear which caused by the abrasion of SiC particles. Due to the low cutting temperature, the graphitization of PCD tools does not happen. The wear mechanism of PCD tools will be the abrasive and adhesive wear.