Unit1AdvancedStructuralCeramics先进结构陶瓷.PPT

Unit 11 Advanced Structural Ceramics 先进结构陶瓷 1、Structural components derived from engineering ceramics are used as monoliths, coatings and composites in conjunction with or as replacements for metals when applications rely on mechanical behavior of the ceramics and their refractory properties, that is chemical resistance to the working environment . 当材料的应用性能依赖于陶瓷的机械性能和它们的难熔性时，由工程陶瓷组成的结构部件可用于与金属结合的或者部分取代金属的块体材料、涂料和复合材料。所谓难熔性是指对工作环境的化学抵抗能力。 Nickel superalloys are currently the main high-temperature materials for components such as combustors in gas turbine engines. They have melting points around 1573 K and a maximum working temperature near 1300 K. 镍基超耐热不锈钢是目前用于生产元件的主要高温材料，例如燃气涡轮机中的喷射引擎燃烧室。它们的熔点在1573k左右，最高工作温度为1300k左右。 Compared with metals, ceramics are generally more resistant to oxidation, corrosion, creep and wear in addition to being better thermal insulators. 与金属相比，陶瓷一般具有更好的耐氧化性、耐腐蚀性、抗蠕变性、耐磨性，除此之外还是良好的热绝缘材料。 They have higher melting points and greater strength than superalloys at elevated temperature so that a major potential application, particularly for silicon nitride, is in gas turbine and reciprocating engines where operating temperatures higher than attainable with metals can result in greater efficiencies. 在高温下和超耐热不锈钢相比它们有更高的熔点和强度，因此，主要的潜在应用（特别是对于氮化硅）是应用在燃气涡轮和往复式发动机方面，在这方面陶瓷的操作温度比金属的操作温度更高，导致机械效率更高。 This enhanced strength is shown in figure for hot-pressed silicon nitride (HPSN), hot-pressed silicon carbide (HPSC), hot isostatically pressed silicon nitride (HIPSN), sintered silicon nitride (SSN), sintered silicon carbide (SSC), reaction-bonded silicon nitride (RBSN) and reaction-bonded silicon carbide (RBSC) . 从热压氮化硅、热压碳化硅、热恒压氮化硅、烧结氮化硅、烧结碳化硅、反应结合氮化硅和反应结合碳化硅图标上看到出：它们的强度确实有所提高。 Although ceramics offer improvements in engine efficiency, incorporation of silicon nitride over the past three decades has been slow, mainly because of the difficulty in reproducible fabrication of dense components to close dimensional tolerances. 尽管陶瓷可以提高发动机效率，但是在过去的3