本文選題：重結晶燒結SiC + SiC漿料��； 參考：《北京理工大學》2015年碩士論文

【摘要】：重結晶燒結SiC陶瓷材料（Recrystallized Silicon Carbide, RSiC）具有耐高溫、硬度高、力學性能優(yōu)良、開氣孔率高，純度高等優(yōu)點，十分適合于制備金屬/陶瓷雙連續(xù)相復合材料。制備孔隙率適宜的SiC陶瓷是制備綜合性能優(yōu)異的雙連續(xù)相復合材料的關鍵之一，但對獲得不同孔隙率的RSiC陶瓷材料以及其微觀結構和力學性能的研究較少，針對這方面的空白，本文通過調節(jié)制備工藝參數(shù)，制備出不同孔隙率的RSiC陶瓷，并對其微觀形貌和力學性能進行研究。 RSiC陶瓷燒結為蒸發(fā)凝聚機理，必須有不同粒徑的SiC顆粒的參與，本文以中位徑為140μm和5μm的SiC為原料，采用注漿成型制備RSiC陶瓷坯體，并在氣氛燒結爐中進行重結晶燒結制備RSiC陶瓷材料。本文主要研究了分散劑的添加量，漿料PH值對SiC漿料流變性能的影響，確定最優(yōu)的分散劑添加量和漿料PH值，探討漿料固相含量對RSiC陶瓷坯體的密度和微觀結構的影響；研究了細顆粒的含量、漿料固相含量和燒結溫度對RSiC陶瓷的孔隙率，微觀結構和力學性能的影響，成功制備出孔隙率在15%-38%的RSiC陶瓷材料。 研究發(fā)現(xiàn)，添加0.2wt%的四甲基氫氧化銨（TMAH）作為分散劑，調節(jié)漿料PH值至9，可獲得流變性能良好，粘度低，觸變性好，適合于注漿成型的SiC漿料。調節(jié)漿料的固相含量，，發(fā)現(xiàn)固相含量70%以下的SiC漿料粘度較低，適合注漿成型，其坯體密度隨著固相含量的增加呈現(xiàn)先增大后減小的趨勢，當固相含量為67.5%時，坯體致密度最高，可達75%，但微觀結構均勻性最好的則是固相含量為65%漿料制備的坯體。 研究表明，通過調節(jié)細顆粒的含量和漿料固相含量，可以在較大范圍內調節(jié)RSiC陶瓷的孔隙率，細顆粒含量為20%-50%，漿料固相含量為60%-69%的范圍內，增加細顆粒含量和漿料固相含量都可以降低RSiC陶瓷的孔隙率，提高燒結頸的發(fā)育程度，進而提高RSiC陶瓷的力學性能，制備的RSiC陶瓷最高壓縮強度和彎曲強度分別為350MPa和115MPa。在2250℃-2350℃進行重結晶燒結，燒結溫度對RSiC陶瓷的孔隙率影響不大，隨著燒結溫度的提高，RSiC陶瓷的力學性能略有提高。
[Abstract]:Recrystallized SiC ceramics (RSCC) have the advantages of high temperature resistance, high hardness, excellent mechanical properties, high porosity and high purity, so it is suitable for the preparation of metal / ceramic dual continuous phase composites. The preparation of SiC ceramics with suitable porosity is one of the key points in the preparation of dual continuous phase composites with excellent comprehensive properties. However, there are few studies on obtaining RSiC ceramics with different porosity and their microstructure and mechanical properties. In this paper, RSiC ceramics with different porosity were prepared by adjusting the process parameters, and their microstructure and mechanical properties were studied. The sintering mechanism of RSiC ceramics must include the participation of SiC particles of different diameters. In this paper, SiC with medium diameter of 140 渭 m and 5 渭 m was used as raw materials to prepare RSiC ceramic billets by grouting molding. RSiC ceramics were prepared by recrystallization sintering in atmosphere sintering furnace. In this paper, the effects of the amount of dispersant and the PH value of slurry on the rheological properties of SiC slurry were studied, the optimum amount of dispersant and the pH value of slurry were determined, and the effect of solid content of slurry on the density and microstructure of RSiC ceramic billet was discussed. The effects of fine particle content, slurry solid content and sintering temperature on the porosity, microstructure and mechanical properties of RSiC ceramics were studied. The RSiC ceramics with porosity ranging from 15% to 38% were successfully prepared. It was found that adding 0.2 wt% tetramethylammonium hydroxide (TMAH) as dispersant, adjusting the PH value of slurry to 9, the SiC slurry with good rheological property, low viscosity and good thixotropy could be obtained. By adjusting the solid content of slurry, it is found that the viscosity of SiC slurry with solid content less than 70% is lower, which is suitable for grouting molding. The density of the slab increases first and then decreases with the increase of solid content. When the solid content is 67.5%, The density of the billet is the highest, up to 75%, but the best microstructure homogeneity is the solid content of 65% slurry. The results show that the porosity of RSiC ceramics can be adjusted in a wide range by adjusting the content of fine particles and the solid content of slurry. The content of fine particles is 20-50 and the solid content of slurry is 60-69%. Increasing the content of fine particles and the solid content of slurry can decrease the porosity of RSiC ceramics, improve the development of sintered neck, and then improve the mechanical properties of RSiC ceramics. The maximum compressive strength and bending strength of the prepared RSiC ceramics are 350MPa and 115 MPA, respectively. Recrystallization sintering at 2250 鈩

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