Competitive advantages of using the hypereutectic Si-Al alloys cylinder sleeves in engine components:
A lightweight cylinder block can be achieved.
In comparision of cast iron cylinder liner,the thermal conductivity and coefficient of thermal expansion is far higher and greater than that of cast iron ones,a good tight contact between the cylinder liner and cylinder block body can be achieved upon temperature elevation and, thus, an internal-combustion engine having a good heat-dissipation characteristic can be provided.
In the condition of ultra-mild wear(UMW),the microstructure(SEM) shows the silicon particles of Al-25%Si alloy is effective maintaining a minimal surface damage,thus,improve the wear-resistance.
As we mentioned earlier, the inner-wall temperature of Al-25%Si alloy cylinder liner can be kept low and the life of the lubricating oil can be prolonged.
By using the hypereutectic Al-25%Si alloy cylinder liners,thanks to the friction coefficient is low, the friction loss which occurs between the piston rings and the cylinder liner can be lessened and, thus, the mileage can be improved.
Mechanical properties of hypereutectic Al-25%Si alloy is as below,
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Mechanical Properties of hypereutectic Al-25Si alloy |
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|
Material |
Density |
Tensile |
Yield |
Poisson's |
Elongation |
Elastic |
Hardness |
|
|
Al-25%Si |
2.64 |
480 |
441 |
0.29 |
0.7 |
96 |
2.6 |
|