外文翻譯---碳結(jié)構(gòu)和固體顆粒侵蝕的保護(hù)高度多孔炭碳復(fù)合保溫材料的使用-材料科學(xué)-文庫吧
2025-04-17 09:01 本頁面
【正文】 the turnaround time of batch processes or as an integral part of the heattreatment regime. The advantage of gas quenching during heat treatment, as opposed to an oil quench, is that the cooling rate can be controlled。 therefore, it is possible to reduce warping and cracking in the ponent . During gas quenching, parti culate matter may bee entrained in the gas ?ows, and impingement with the insulation may result in material removal. In the challenging environment of gas quenching, there is a requirement for erosion protection of the CBCF by the use of higher density carbonbased coating and cladding , ductile and brittle materials exhibit different erosion characteristics。 of particular interest is their relationship between the erosion rate and the angle of incidence [15]. Ductile materials tend to display maximum erosion at glancing angles of impact, approximately 30176。 for metals, and material removal is thought to occur by a micromachining mechanism with a contribution of deformation wear at higher angles. On the other hand, for brittle materials, maximum erosion is found where the erodent stream is perpendicular to the erosion surface, and material removal typically results from the formation of Hertzian or lateral cracks . Although it is a convenient approach to idealize materials erosion behaviour in this manner, it is an oversimplification, because erosion is found to depend on other factors, including the erosion conditions, such as erodent par ticle size and shape, as well as the details of the microstructure of the target material . This paper is concerned with the examination of the microstructure and the efectiveness in improving the erosion resistance of several candidate coatings and claddings. The results presented involve the steady state erosion rate as a function of impingement angle under defined conditions. The overall aim of this work is to relate the microstructure to the erosion data by means of a mechanistic approach .materials included the Fiber Materials Inc. C3 posite], which is resin impregnated, and the Toyo Tanso G3470 . In addition, a highdensity carbon— carbon posite was produced by employing CVD over a period of 800 h to infiltrate a 5 mm thick section of the CBCF substrate to a density of 1 Mg m\3. The CVD process used natural gas as the carbon precursor and nitrogen as the carrier gas. The densification was carried out at approximately 1100 176。C under a reduced. 2. Experimental procedure . Materials The CBCF used as the substrate was a standard mercial material (density Mg m\3) manufactured by Calcarb Ltd. The coating and cladding materials were applied to the xy plane of the CBCF substrate (see the schematic diagram of CBCF structure in Fig. 1)。 the xy plane is perpendicular to the direction of minimum thermal conductivity and hence is most likely to be the exposed surface of the insulation in a furnace. The coating and cladding materials exam ined in this paper were all carbon based and they are listed in Table I. The coating materials are defined as those that bond independently to the CBCF substrate,whereas the claddings are bonded b
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