英语翻译In the same figure it is apparent that the specimens con

英语翻译
In the same figure it is apparent that the specimens containing larger amounts of Al2O3(βα460 and βα230),which have a composition close to the composition of the eutectic liquid(Al2O3/Y2O3:60/40),show,as may be expected from the Y2O3–Al2O3 phase diagram(Fig.8),a higher final density than those having Y2O3–Al2O3 in the YAG stoichiometric ratio,particularly in the mid temperature range(1775–1850℃),above the eutectic temperature.Nonetheless it may also be pointed out that for all compositions the use of too high sintering temperatures again encourages SiC grain growth so hindering densification.
Additionally,it can also be seen that adding C to these basic compositions always produces a beneficial effect on densification,probably due to the formation of liquids of lower viscosity as reported by Misra,who studied the densification of SiC with additions of Al2O3 and C.It is important to point out that in the present work the enhancement in densification due to the addition of C to the system SiC–Y2O3–Al2O3 takes place at even lower temperatures than those reported by this author.
It may also be worth mentioning that,as reported elsewhere important weight losses were observed,ranging from 2wt% at 1750℃ to 12wt% at 2050℃,during Pressureless Sintering of these specimens(Fig.9).
Besides,as the amount of Al2O3 and C was increased the weight losses observed also increased.These losses may be understood due to the progress of several possible chemical reactions taking place in the experimental temperature range used.In contrast,at the lower temperatures,the SiC/Al2O3 interface becomes unstable when carbon activity is high and Al2O3 would be converted to Al4C3.On the other hand,at higher temperatures,as reported by Van Dijen the reaction:
SiC+Al2O3→SiO(g)T+Al2O(g)T+CO(g)
may be taking place causing the volatilisation of gaseous species like SiO,Al2O and CO.Nevertheless,as shown in Fig.10,in the present work it was clear that adding Y2O3 had an additional effect leading to the formation of Al2Y6C,probably as a result of the following reactions:
Al2O3+C→Al2OC+O2(g)
Al2OC+2Y2O3→Al2Y6C+5/2O2(g)
in which C may participate either,from SiC itself or as the extra C added.

在同一图中,我们可以明显的看到,反应样本中Al2O3(βα460和βα230)含量更多,化学构成与共溶液(Al2O3/Y2O3:60/40)十分相近,如同我们可以从Y2O3–Al2O3关系图(图8)中推断的,在共熔温度范围内,尤其是中等温度范围内(1775–1850℃),与反应样本中Y2O3–Al2O3含量高时相比,最终产物会呈现出密度更高的特性.
但是,我们也应指出,无论反应物的化学成分如何构成,烧结时的高温都会促进SiC的晶粒生长而达到抑制稠化的效应.
此外,我们也应看到,正如从事添加Al2O3和C后的稠化效应研究的Misra所说的那样,对反应物中加入C会对稠化效应产生积极影响.
同时,指出在目前的情况下,通过在SiC–Y2O3–Al2O3体系反应物中加入C来加强稠化作用,实际反应温度要比他所研究得出的温度低,也是十分重要的.
也有必要提到,另有报告指出,在样本的无压烧结中,亦会发生重要的重量减轻现象,在1750℃为2wt%,2050℃时为12wt%(图9).
此外,随着反应物中Al2O3和C量的增加,这样的重量减轻也在加剧.这样的重量减轻可理解为,在实验温度下,随着主反应的发生,另有其他多个的可能的化学反应正在发生.
但是,在低温时,the SiC/Al2O3表面会产生不稳定而C的活性则相当高,因此Al2O3会被转化成Al4C3.另一方面,在高温时,如Van Dijen研究所得出的以下反应有可能会发生：
SiC+Al2O3→SiO(g)T+Al2O(g)T+CO(g)
并导致气态的反应物如SiO,Al2O and CO挥发.然而,如图10所示,在现今反应中,加入Y2O3对生成Al2Y6C的反应产生积极影响的现象,也是十分明显的.而该影响极有可能是因为如下的反应也在发生：
Al2O3+C→Al2OC+O2(g)
Al2OC+2Y2O3→Al2Y6C+5/2O2(g)
在反应中,C或者由SiC中的C反应得来,亦或是反应物中加入的C.