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本文说明绝热机用活塞陶瓷与金属的连接方法和该种活塞的潜力。虽然研究出了多种陶瓷和金属的连接方法,但是化学结合的方法,如钎焊和扩散压合不仅连接过程复杂和不耐高温,而且也不能得到陶瓷所需的196MPa 的连接强度。例如,常用的机械方法,是加撑来连接陶瓷与金属,但这种连接会由于金属塑性变形后剪切力加大而损坏陶瓷的接合面。因此,有必要减小陶瓷与金属材料之间的剪切力和改进金属的塑性。采用这种连接方法,陶瓷与金属相接触后,金属瞬时受热硬度就降低,具有韧性,因而金属在外力的作用下将具有陶瓷的形状。预期陶瓷连接面加槽可以进一步改进连接强度。这种连接方法的特点是:无需选择陶瓷材料、缩短连接时间和高温寿命长。上述方法制出的陶瓷绝热活塞,仅在与燃气直接接触的活塞顶部采用陶瓷材料,裙部是用廉价的韧性金属制成的,活塞顶部和裙部连接面之间用隔热材料衬垫。因此,制成了很简单而寿命长的隔热陶瓷活塞。全世界开发绝热柴油机的速度似乎稍放慢,有人对它是否能改进性能和提高燃油经济性持怀疑态度。然而,作者所研究的、且经3000h 以上耐久试验的陶瓷绝热涡轮复合发动机,最后已进入了性能试验的阶段。起初,绝热机开始预定的试验前,就由于陶瓷零件缺乏足够的机械强度和耐热强度而损坏,迫使发动机停车,这就需要花费许多时间和精力来改进陶瓷零件的强度。即便解决了陶瓷的强度问题,陶瓷发动机的许多其他问题,例如绝热性能、陶瓷与金属的连接方法、成本、可靠性以及改进性能和提高燃油经济性的潜力等仍有待于解决。其中,制造陶瓷与金属的连接件对于将来解决所有绝热发动机的问题是首要条件。绝热活塞分为陶瓷顶部和金属裙部,必须把这两部分完全可靠地连接起来。本文说明可经受高温和高机械应力的陶瓷与金属的连接件以及活塞用陶瓷与金属的新连接方法。
This article describes the connection method of piston ceramic to metal for insulation machines and the potential of such pistons. Although a variety of ceramic and metal connection methods have been developed, chemical bonding methods such as brazing and diffusion bonding not only complicate the connection process but also impatience with high temperatures, and also fail to achieve the 196 MPa connection strength required for ceramics. For example, a commonly used mechanical method is to use braces to connect ceramic to metal. However, such a connection may damage the bonding surface of the ceramic due to the increased shear force caused by plastic deformation of the metal. Therefore, it is necessary to reduce the shear force between the ceramic and the metal material and to improve the plasticity of the metal. Using this connection method, ceramic and metal contact, the metal instantaneous heat hardness is reduced, with toughness, so the role of metal in the external force will have a ceramic shape. It is expected that the ceramic connecting surface plus groove can further improve the connection strength. This connection method is characterized by: no choice of ceramic materials, shorten the connection time and high temperature life. The ceramic heat-insulating piston produced by the above method is made of ceramic material only on the top of the piston in direct contact with the gas, the skirt is made of cheap tough metal, and the top of the piston and the skirt connecting surface are padded with thermal insulation material. Therefore, a very simple and long-life insulated ceramic piston is made. There seems to be a slight slowdown in the development of adiabatic diesel engines around the world, with some doubting whether it will improve performance or increase fuel economy. However, the ceramic adiabatic turbo compound engine that the author studied and endured for more than 3000 hours has finally entered the stage of performance test. Initially, before the adiabatic machine started a predetermined test, the engine was stopped due to the lack of sufficient mechanical and thermal strength of the ceramic parts, which required much time and effort to improve the strength of the ceramic parts. Even if the problem of ceramic strength is solved, many other problems of ceramic engines such as thermal insulation, ceramic-to-metal connection, cost, reliability and potential for improved performance and fuel economy are still to be solved. Among them, the manufacture of ceramic and metal connectors for the future to solve all adiabatic engine problems is the first condition. Insulated piston is divided into ceramic top and metal skirts, these two parts must be completely and reliably connected. This article describes ceramic-to-metal connectors that can withstand high temperatures and high mechanical stresses, and new methods of joining ceramics to metals for pistons.