Process Of Preparation Of SiCp/Al Composite Gel System

SiCp/Al composite materials have excellent properties, such as mechanical,thermal and optical properties in the fields of aerospace, advanced weapons systems,automotive, electronic packaging and sports equipment industy. However, there are alsomany problems for the SiCp/Al composite materials in preparation and application.Such as inhomogeneous distribution of SiC grain in Al matrix, poor bonding strength ofthe interface between SiCp and Al matrix, bad machining performance and poordimensional stability of products. The experts and scholars have pay attentions to newpreparation technology of SiCp/Al composite materials in recent years. In this study,gel-casting method has been brought into the mixing process of material to prepareSiCp/Al composite materials. The effect of the composition of raw materials andprocess of the preparation on the dispersible uniformity, bulk density of compositepowder and the density of composite materials were investigated.SiCp was pretreated by acid corrosion, distilled water immersion, ultrasonictreatment so that small SiC particles and impurities should be removed from thematerials. The coating process is high concentration induced2wt.%polymerization ofAM on the surface of SiCp. The SiCp is packaged in the organic components to easilyget dispersible uniformity.Composite powder can be obtained from the preparation of slurry wet mixing,drying and degreasing. Experimental results show that the stability of slurry suspensioncan attain90%of the ideal value when the amount of dispersant is2.0wt.%. And ittakes shorter time for water used in slurry than anhydrous ethanol. It is about15mins.The dispersion degree is also better.The colloidal component and environmental temperature have an effect on drying,debinding process. The final drying process parameters are: for using anhydrous alcoholas the dispersion medium,24℃/24h,70℃/24h;for using deionized water as thedispersion medium,25℃/48h and70℃/48h.The optimal debinding can be achievedunder the condition of body colloid composition of2wt.%, anhydrous ethanol asdispersion medium. XRD results show that the components of the body did not change significantly after drying and debinding.The content of the enhanced phase changes in the range of17vol.%~33vol.%. Thebulk density changes in0.59~0.62. SEM results show that, although the organicingredients in powder cannot be completely removed, the two phases disperseuniformly.In the pressing and sintering process, the green density increases as pressureincreases in the range of20~60MPa for pressure. The maximum value is up to95%oftheoretical density. The density of the green body decreases with increases of enhancedcontent. The green density is between95%~94.3%for enhanced phase content in therange of17vol.%~25vol.%. And SiC particles disperse uniformly in Al matrix. Thebody porosity increases with increase of sintering temperature and the amount of AMincrease. But the maximum is less than5.2%.