1. 研究目的与意义（文献综述）

the piston is the central part of the automobile engine, which plays an important role in the engine work.when the engine is working,the high temperature gas (instantaneous high temperature up to 2300℃) directly acts on the piston,the top temperature rose (up to 290℃～400 ℃), and the temperature distribution is not uniform; the top of the piston bears very large air pressure when engine is working.the pressure of gasoline engine and diesel engine is very large(gasoline pressure 4mpa～ 5mpa,diesel engine 8mpa ～9mpa);besides,the piston moves very fast in the cylinder（11m/s～16m/s）.the piston is subjected to high temperature, high pressure,corrosion,wear and other alternating mechanical load and thermal load,the working environment is very bad.therefore,the engine engine piston material requirements are also very harsh,should have a small coefficient of thermal expansion,low density,good thermal conductivity, high temperature strength, good corrosion resistance and wear resistance,high dimensional stability characteristics^[1,2].

the early car engine pistons were mostly made of cast iron or cast steel^[1-5].it has the characteristics of high thermal strength and good wear resistance, but the density and linear expansion coefficient are larger；later, with the emergence of aluminum products,a large number of aluminum engine made of engine piston into the market,with low density,good thermal conductivity,linear expansion coefficient is small,but its poor wear resistance and heat intensity is not high；with the development of science and technology,aluminum matrix composites have entered the stage of human being,and the aluminum matrix composites have excellent properties.the piston made of aluminum composite material has many advantages such as high heat intensity,small density,good wear resistance,good thermal conductivity and small linear expansion coefficientbut the cost is high, the process is complex,the process is not perfect,and it also shows that the aluminum matrix composite will become a development trend^[6-8].

at present, more research is the use of sic,al₂o₃ particles reinforced aluminum composite materials.duralcan company use 20%sicp and a356al produced sicp/a356al composite,the yield strength is 75% higher than matrix aluminum alloy,the elastic modulus is increased by 30%,the thermal expansion coefficient is decreased by 29% and the wear resistance is increased by 3 to 4 times^[9].li^[10] use the sicp/a356al composites with particle content of 40vol% were prepared by vacuum semi-solid stirring casting method,10vol%、20vol%、30vol% particle content composite derived materials produced by dilution method,the results show that the composite material with the content of 20vol% is best,the tensile strength is higher (296mpa), the hardness is higher (121.5hb),but the elongation is lower (1.08%).ouyang^[11]use al₂(so₄)₃ powders through stirring casting method and in situ reaction method produced al₂o₃ reinforced aluminum matrix composites,it had good impact toughness and good wear resistance.but these results still can not get rid of complex components involved,the preparation process is not perfect,the development cost is too high,so it still in the automotive field has not been widely used today.

2. 研究的基本内容与方案

一、Basic content

1.Analysis and comparison of the basic properties of engine piston material.

2.Preparation of Ti₃SiC₂ reinforced aluminum matrix composites for engine piston.
3.Study on the properties of Ti₃SiC₂ reinforced aluminum matrix composites for engine piston.

Technical scheme:

The first step：Mixed Ti₃SiC₂ and Al powder by rollig ball mill，The initial volume fraction of Ti₃SiC₂ was 10Vol%-40Vol%.After completion,using a certain abrasive tool to press the powder material into the blank shape and prepare the sintering.

The second step：The material was sintered by vacuum hot pressing furnace.Heated to a certain temperature, after a period of time to stop creation of vacuum,at the same time inlet argon to the furnace,keep warm for a while,when the furnace is cooled to 80℃,in sampling.

The third step：Study the reaction mechanism of Ti₃SiC₂ and Al Aluminum matrix composites.Determination of hot pressing process and key process parameters.Study the temperature, holding time and path on the phase composition,microstructure and properties of the composites.Propare Ti₃SiC₂/Al composites and test density,hardness and mechanical properties of composites.Specific methods is：analyze the phase of the composites by XRD;observe and analyze the microstructure of materials by SEM；surface scanning of materia by EDS,analyze the content of elements in different regions of the samples；the hardness of the composites is measured by the Vivtorinox hardness tester,and the density of the composites is measured by Archimedes method and the basic mechanical properties of materials were tested by universal testing machine like bending strength,compressive strength,etc.

Finally,complete graduation thesis writing and improvement.

3. 研究计划与安排

4. 参考文献（12篇以上）

1.陈琪云.铝合金活塞材料的研发与应用进展[j],合肥学院学报,2012,22(3).

2.任书坤.汽车发动机活塞用铝合金[j],汽车技术,1994,4.

3.陈长江,王渠东,尹东弟,等.内燃机活塞材料的研究进展[j],材料导报：综述篇，2009，23（8）.