而且气门头部容易被经过的高温气体烧蚀，活塞顶部也可能会碰到气门使发动机严重损坏。

Also the valve heads will be liable to be burnt by the passing hot gases, and there is the likelihood of the piston crown touching an open valve, which can seriously damage the engine.

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此外气门头易于被通过的热气体燃烧，这有可能使活塞频繁冲击打开的气门，使发动机严重损坏。

Also the valve heads will be liable to be burnt by the passing hot gases, and there is the likelihood of the piston crown touching an open valve, which can seriously damage the engine.

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气门头可通过一次压制和烧结、两次压制和烧结、锻造和机加工、锻造和烧结及动磁压制成形和烧结而制成。

The valve head may be made by single press and sintering, double press and sintering, forging and machining, forging and sintering, and dynamic magnetic compaction and sintering.

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