碳化硅粉体整形的熔盐法工艺研究

发布时间：2018-02-02 21:04

  本文关键词： β-SiC粉体 整形 熔盐法　出处：《西安科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：碳化硅材料具有良好的化学稳定性、耐磨性,耐高温、高强度和高的导热系数等优异性能,在机械、电子、能源、航天航空、空间技术以及汽车工业等领域具有广泛应用。原材料碳化硅粉体的粒径、形貌、纯度对碳化硅材料的影响至关重要,目前行业中使用的碳化硅粉体颗粒存在粒径分布不均、球形度不好、片状和条状大量存在等问题,难以制备高密度碳化硅材料,严重影响了碳化硅优异性能的发挥。因此有必要对碳化硅粉体进行整形以获得组织致密、性能优异的碳化硅陶瓷。为此,本文提出用熔盐法对SiC粉体整形的新方法,研究了熔盐种类、配比、反应温度以及保温时间等工艺参数对SiC粉体颗粒的影响。采用激光粒度分析、SEM、XRD、堆积密度、热力学计算等分析手段对整形后β-SiC粉体颗粒的形貌、大小以及成分进行表征分析,得出了相应结论:在NaCl-KCl熔盐体系中,对β-SiC原粉(D50为37.63μm,堆积密度为1.2g/cm3)进行整形,结果表明NaCl-KCl熔盐对原粉有细化作用,熔盐配比为1:1.2、温度800℃、保温10h时整形效果最佳,整形后得到D50为28.56μm、堆积密度为1.81g/cm3的β-SiC粉体,粒径分布均匀,颗粒表面整洁光滑接近球形,纯度提高了 6.78%。在Na2CO3-K2CO3-CaCO3熔盐体系中,对β-SiC原粉进行整形,结果表明Na2CO3-K2CO3-CaCO3熔盐对原粉颗粒有长大作用,熔盐比例为1:1.2、温度700℃保温12h,其堆积密度增大到1.78g/cm3,且平均粒径分布均匀,形貌平整接近球形,D50由原来的37.63μm变为42.92μm,纯度提高了 7.25%,结晶性能良好。在NaNO3-KNO3熔盐体系中,对β-SiC原粉进行整形,结果表明整形后晶粒尺寸没有明显的变化,但粒径分布较好。熔盐配比为1:1.6、温度390℃保温10h,NaNO3-KNO3熔盐使β-SiC粉体颗粒表面平整,接近球形,平均粒径分布均匀,堆积密度增大到1.72 g/cm3,纯度较高,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，

本文编号：1485474