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内燃机车柴油机的结构件已广泛采用铝基合金材料,这是因为硅铝合金具有很好的工艺性和工作性能。硅作为主要的合金成分,它能保证零部件材料具有很高的液态流动性、低的线性收缩率及可焊性好等优点。当零件材料成分中硅含量为6％～12％时线性收缩率(在结晶过程中)为3％～4％;当硅含量为20％～24％时,收缩率仅为1％～2％。硅还具有线膨胀系数低的特点。这对于工作温差大(如柴油机活塞)条件下的部件而言是极为重要的。此外,由于硅导热系数高,故有助于活塞的有效冷却。
The structural parts of diesel locomotive diesel engines have been widely used aluminum-based alloy material, which is because silicon aluminum alloy has good processability and performance. Silicon as a major component of the alloy, it can ensure the components of the material with high liquid flow, low linear shrinkage and weldability and so on. The linear shrinkage (in the crystallization process) is 3% -4% when the content of silicon in the material composition is 6% ~ 12%, while the shrinkage is only 1% ~ 2% when the silicon content is 20% ~ 24% . Silicon also has the characteristics of low linear expansion coefficient. This is extremely important for components with large operating temperatures (such as diesel pistons). In addition, due to the high thermal conductivity of silicon, it contributes to the effective cooling of the piston.