重結(jié)晶碳化硅凝膠注模成型工藝及其性能研究原創(chuàng)學(xué)術(shù)論文-閱讀頁
2025-01-28 19:51本頁面
【正文】 )。微粒的自由表面一般呈凸形，微粒越小，彎曲越凸，微粒上的氣壓就越高。坯體中細粒可均勻藏于粗粒的三角空隙中，當(dāng)達到一定溫度時，帶凸面的顆粒處的SiC汽化，而蒸汽在帶凹面及平坦表面的顆粒處凝結(jié)。 （a）固相體積分數(shù)為55Vol.% （b）固相體積分數(shù)為70Vol.%圖6 RSiC燒結(jié)體斷口形貌（SEM）圖6示出固相體積分數(shù)為55Vol.%和70Vol.%的坯體在2450℃和氬氣氛保護下燒結(jié)得到的重結(jié)晶SiC高溫材料的斷口形貌。而圖6（a）中由于懸浮體的固相體積分數(shù)較低，懸浮粒子有相當(dāng)程度的沉降，粗細顆粒分散不均勻，燒結(jié)后材料的氣孔率較70Vol.%要大，氣孔分布不均勻，且晶面存在內(nèi)部缺陷，強度也不高（ MPa）。當(dāng)重結(jié)晶SiC固相體積分數(shù)由55Vol.%增加到70Vol.%時， g/ g/cm3， 。結(jié)果表明，在假定條件下SiC濃懸浮體的固相體積分數(shù)與粘度的關(guān)系與高剪切極限時的Quemada模型較為相符。沉降實驗表明，該濃懸浮體中粗細顆粒間能達到均一穩(wěn)定的分散，漿料不會產(chǎn)生明顯地沉降，其穩(wěn)定性和流動性都符合凝膠注模成型復(fù)雜形狀坯體的注模要求。綜上研究結(jié)果表明，凝膠注模成型適用于重結(jié)晶SiC高溫材料的膠態(tài)成型，且工藝簡便，快速。s College, Yunnan, 661100)Abstract: It was described that study on gelcasting of recrystallized silicon carbide in this paper. The slurries were characterized for the state of their dispersion by employing the various quantitative diagnostic techniques . zeta potential, rheological behavior and sedimentation. The sintered mechanism of RSiC was discussed. The results of study showed that a concentrated suspension of solid volume loading 70Vol.% was prepared when slurry was adjusted to pH= via addition of a proper amount of dispersants. The results of sedimentation indicated that coarser particles of SiC could be dispersed stably in the highsolidloading suspension and had no obvious sedimentation. The high temperature material of RSiC with bulk density and MPa flexiual strength was obtained by sintering of green bodies prepared by gelcasting at temperature of 2450℃ and in atmosphere of Ar. Key words: Gelcasting；Recrystallized silicon carbide；Rheological property； Sedimentation
公司管理相關(guān)推薦
鄂ICP備17016276號-1