英语翻译It is also worth mentioning that by comparing Fig.1a,b a

英语翻译
It is also worth mentioning that by comparing Fig.1a,b and Figs.4 and 5,different densification behaviour and microstructure evolution is observed for materials made from b or β+α SiC initial powders.Two main differences can be emphasised between these powders; on the one hand their crystal structure and on the other,the higher free carbon and lower oxygen content of the β-SiC powder from Superior Graphite(1.62w/o C,0.9w/o O),as compared to the β+α SiC powder from Lonza(no free carbon and 1.5w/o O).The samples made with β-SiC from Superior Graphite can only be densified up to a maximum temperature of 1750℃.From Figs.3a and 4b,the polytype transformation 3C→4H that occurs above this temperature,and may be encouraged by the presence of Al2O3 and C,produces an extensive grain growth.This effect counteracts the densification process.In contrast,for the β+α-SiC powder,although the α→β transformation is completed at 1800℃(mainly the 3C→6H transformation),the polytype product of the reaction is the 6H,which according to microstructural examinations does not induce significant grain growth at this temperature,thus allowing the densification to progress.Related to this behaviour,the microstructure at 1800℃ consists of equiaxed grains with a much lower final grain size(Fig.5a) than that of the β-SiC powder mixtures sintered at the same temperature,in which clearly elongated grains are developed(Fig.4b).Additionally,at higher temperatures the 6H→4H transformation takes place(Fig.3b) and noticeable grain growth is observed,which is enhanced at these temperatures by the carbon addition,revealed from Figs.5 and 7.

同时,我们也值得提到,对比图1a,b和图4,图5,同样由β或β+α SiC反应物在反应中稠化作用和产物的微观结构是各不相同的.
我们应强调反应物的两个主要不同点.第一是反应物粉末的构成；一方面是它们的晶体结构不同,另一方面,它们可能是来自Superior Graphite公司的的单体碳和低氧β-SiC粉末(1.62w/o C,0.9w/o O),也可能来自Lonza公司的β+α SiC粉末(无单体碳,1.5w/o O).
如果样本主要由Superior Graphite的β-SiC构成,那么它的最高稠化温度为1750℃.
如图3a和图4b所示,3C生成4H的反应只在此温度以上发生,并容易被Al2O3和C的加入使反应加剧,产生更剧烈的晶粒生长.而这一反应将阻碍稠化反应.
相反,对β+α-SiC而言,虽然α生成β的反应在1800℃即告完成(主要是3C生成6H的反应),但是,主要的产物为6H,而根据微观结构试验,在该温度下,它不会促使剧烈的晶粒生长发生,因而使得稠化作用得以进行.
与此作用密不可分的是,在1800℃时,β+α-SiC的微观等轴晶结构由更小的晶粒构成(图5a),而β-SiC的混合物在同一温度下,由伸长晶粒构成(图4b)
此外,如果温度继续增加,6H生成4H的反应将会发生,也能观察到明显的晶粒生长,随着C的加入,该反应在此温度下被加剧,所图5和图7所示.
附,关于Superior Graphite(高级石墨)和Lonza(龙沙)公司的介绍
Superior Graphite specializes in high temperature technologies,advanced sizing,blending,and coating technologies,providing you with the highest value graphite and carbon product solutions.
Throughout its long history,Superior Graphite has been committed to three core principals:ingenuity,versatility,and integrity.This has enabled us to adapt to ever-changing business and economic conditions,and led to a process of continuous growth and evolution with our customers.
Since its foundation in 1917,our company has explored the physical and geographical frontiers of its markets.In the late 1970s,this pioneering approach led to the invention of a new,patented furnace technology that revolutionized our product range and transformed the company (Until then,graphite was mainly processed from natural mineral resources or the re-crushing of spent electrodes).We were the first to manufacture graphite on a continuous basis using proprietary technology.We subsequently expanded the boundaries of natural and synthetic graphite purification as well as the process of synthesizing graphite or other carbon-based materials.We have also explored new avenues in continuous graphitization and developed a number of innovative processes.
We are committed to continuously collaborate with our business partners,harnessing the challenges of today,and turning them into the opportunities of tomorrow.Solutions from Superior Graphite are tools that will positively impact your success.
Lonza is continually expanding its scientific and technology base,assigning a high priority to advanced R&D as well as state-of the-art plants and equipment to ensure environmentally safe and quality-minded production.Creative thinking,dedicated staff and sound resources are the strengths that Lonza relies on for further growth.Our people are the key to success – they have extensive expertise in multidisciplinary project management,integrating the wishes and know-how of our customers at every stage.