本文關(guān)鍵詞： β-SiC粉體 整形 熔鹽法　出處：《西安科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：碳化硅材料具有良好的化學(xué)穩(wěn)定性、耐磨性,耐高溫、高強度和高的導(dǎo)熱系數(shù)等優(yōu)異性能,在機械、電子、能源、航天航空、空間技術(shù)以及汽車工業(yè)等領(lǐng)域具有廣泛應(yīng)用。原材料碳化硅粉體的粒徑、形貌、純度對碳化硅材料的影響至關(guān)重要,目前行業(yè)中使用的碳化硅粉體顆粒存在粒徑分布不均、球形度不好、片狀和條狀大量存在等問題,難以制備高密度碳化硅材料,嚴重影響了碳化硅優(yōu)異性能的發(fā)揮。因此有必要對碳化硅粉體進行整形以獲得組織致密、性能優(yōu)異的碳化硅陶瓷。為此,本文提出用熔鹽法對SiC粉體整形的新方法,研究了熔鹽種類、配比、反應(yīng)溫度以及保溫時間等工藝參數(shù)對SiC粉體顆粒的影響。采用激光粒度分析、SEM、XRD、堆積密度、熱力學(xué)計算等分析手段對整形后β-SiC粉體顆粒的形貌、大小以及成分進行表征分析,得出了相應(yīng)結(jié)論:在NaCl-KCl熔鹽體系中,對β-SiC原粉(D50為37.63μm,堆積密度為1.2g/cm3)進行整形,結(jié)果表明NaCl-KCl熔鹽對原粉有細化作用,熔鹽配比為1:1.2、溫度800℃、保溫10h時整形效果最佳,整形后得到D50為28.56μm、堆積密度為1.81g/cm3的β-SiC粉體,粒徑分布均勻,顆粒表面整潔光滑接近球形,純度提高了 6.78%。在Na2CO3-K2CO3-CaCO3熔鹽體系中,對β-SiC原粉進行整形,結(jié)果表明Na2CO3-K2CO3-CaCO3熔鹽對原粉顆粒有長大作用,熔鹽比例為1:1.2、溫度700℃保溫12h,其堆積密度增大到1.78g/cm3,且平均粒徑分布均勻,形貌平整接近球形,D50由原來的37.63μm變?yōu)?2.92μm,純度提高了 7.25%,結(jié)晶性能良好。在NaNO3-KNO3熔鹽體系中,對β-SiC原粉進行整形,結(jié)果表明整形后晶粒尺寸沒有明顯的變化,但粒徑分布較好。熔鹽配比為1:1.6、溫度390℃保溫10h,NaNO3-KNO3熔鹽使β-SiC粉體顆粒表面平整,接近球形,平均粒徑分布均勻,堆積密度增大到1.72 g/cm3,純度較高,提高了 6.43%。
[Abstract]:Silicon carbide materials have good chemical stability, wear resistance, high temperature resistance, high strength and high thermal conductivity and other excellent properties in machinery, electronics, energy, aerospace. Space technology and automotive industry are widely used. The size, morphology and purity of silicon carbide powder of raw materials are very important to the influence of silicon carbide material. At present, the silicon carbide powder used in the industry has some problems such as uneven particle size distribution, poor sphericity, large number of sheet and strip, and so on, so it is difficult to prepare high-density silicon carbide materials. Therefore, it is necessary to plastic silicon carbide powder in order to obtain compact and excellent properties of silicon carbide ceramics. In this paper, a new method for shaping SiC powder by molten salt method is proposed. The effects of technological parameters such as the type of molten salt, ratio of molten salt, reaction temperature and holding time on the particle size of SiC powder are studied by laser particle size analysis. The morphology, size and composition of 尾 -SiC powder were characterized by means of SEMS-XRD, bulk density, thermodynamic calculation and so on. It is concluded that the 尾 -SiC powder D50 is 37.63 渭 m and the packing density is 1.2 g / cm ~ 3 in NaCl-KCl molten salt system. The results showed that NaCl-KCl molten salt had fine effect on the raw powder. The best shaping effect was obtained when the ratio of molten salt was 1: 1.2, the temperature was 800 鈩，

本文編號：1485474