Notes

[1] Partially stabilized zirconia (PSZ) has high strength and toughness and better reliability in performance than does zirconia. It is obtained by doping the zirconia with oxides of calcium, yttrium, or magnesium.

句意：部分稳定氧化锆具有较高的强度和韧性，比氧化锆性能更可靠。它是通过对氧化锆进行钙、钇和镁的氧化物掺杂制成的一种新型陶瓷。

[2] Cermets are combinations: a ceramic phase bonded with a metallic phase. Introduced in the 1960s and also called black ceramics or hot-pressed ceramics, they combine the high-temperature oxidation resistance of ceramics with the toughness, thermal-shock resistance, and ductility of metals.

句意：金属陶瓷是20世纪60年代出现的一种由陶瓷相和金属相构成的混合物，又称为黑色陶瓷和热压陶瓷。它们将陶瓷的抗高温氧化性，以及金属材料的韧性、抗热振性和延展性结合在一起。

[3] The development of such an engine has, however, been slower than expected because of such problems as unreliability, lack of sufficient toughness, difficulty with lubricating bearings and hot components, and a lack of the capability for structural ceramics (such as silicon nitride and silicon carbide) to be produced economically in near-net shape, as weighed against the need for the machining and finishing processes required for dimensional accuracy of the engine.

句意：然而，由于性能的不稳定、缺乏足够的韧性、对轴承和热工作部件的润滑困难，并考虑到发动机的尺寸精度、要求最后进行机加工和精整加工，从而缺乏低成本生产、近净成形的结构陶瓷（如氮化硅和碳化硅）的能力，故这种全陶瓷结构的热力发动机的发展进程最终比预期要慢。

[4] However, if the long-chain molecules in a polymer are cross-linked in a three-dimensional arrangement, the structure in effect becomes one giant molecule with strong covalent bonds, these polymers are called thermosetting polymers, or thermosets, because, during polymerization, the network is completed and the shape of the part is permanently set.

句意：然而，如果聚合物的长链分子交联成三维结构，就会成为大分子。这种大分子具有一种强有力的共价键结构，这时的聚合物就成为了热固性聚合物。因为聚合反应时形成了网状结构，所以聚合后的零件形状也就永久保持不变了。

[5] Biodegradability means that microbial species in the environment (e.g., microorganisms in soil a nd water) will degrade a portion of (or even the entire) polymeric material, under the right environmental conditions, and without producing toxic by-products.

句意：聚合物的生物降解性是指环境中的微生物物种（例如，土壤和水中的微生物）在合适的条件下可以降解部分或全部聚合物材料，而不生成有毒的副产品。

[6] These properties can be improved by embedding reinforcements of various types (such as glass or graphite fibers) to produce reinforced plastics. Metals and ceramics, as well, can be embedded with particles or fibers, to improve their properties; these combinations are known as metal-matrix and ceramic-matrix composites.

句意：这些性能可以通过各种形式的包埋增强（例如，加入玻璃或石墨纤维）来得到改善，从而生产出增强塑料。金属和陶瓷也可以采用加入塑料或纤维的方式来提高其性能。这种材料被称为金属基和陶瓷基复合材料。