共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Si3N4/Si3N4陶瓷连接的研究进展 总被引:2,自引:0,他引:2
连接技术是Si3N4陶瓷实用过程中必须解决的难题之一。本文综述了Si3N4/Si3N4陶瓷连接的研究现状以及不同连接工艺对连接强度的影响。 相似文献
3.
4.
5.
《Journal of the European Ceramic Society》2000,20(8):1191-1195
This report describes an investigation of the synthesis of β-Si3N4 particles from α-Si3N4 particles. The β fraction of Si3N4 particles was found to depend on temperature, heating time, and the type of crucibles in which the Si3N4 particles were heated. When Si3N4 particles were heated in a crucible made of carbon, most α-Si3N4 particles converted to β-Si3N4 after heating at 2000°C for 90 min in an atmosphere of N2 of 9 kgf/cm2. The morphology of the resulting β-Si3N4 particles appeared as a whisker shape. When Si3N4 particles were heated in a crucible made of boron nitride, most α-Si3N4 particles converted to β-Si3N4 after heating at 2000°C for 480min in an atmosphere of N2 of 9kgf/cm2. The resulting morphology was equiaxed. It is suspected that the transformation occurs via the gas phase and is affected by the partial pressure of oxygen in the atmosphere. 相似文献
6.
以Y2O3-Al2O3-La2O3体系作烧结助剂,在5.4~5.7GPa、1620-1770K的高温高压条件下进行了α-Si3N4与γ-Si3N4、α-Si3N4粉体的烧结研究,并探讨了烧结温度及压力对烧结体性能的影响。实验结果表明:α-Si3N4、γ-Si3N4完全相变为β-Si3N4;在相同的烧结条件下,α-SigN4比γ-Si3N4、α-Si3N4混合粉体烧结试样的相对密度、维氏硬度高。α-Si3N4与γ-Si3N4、α-Si3N4混合粉体烧结试样的最高相对密度与维氏硬度分别为98.78%、21.87GPa和98.71%、21.76GPa。烧结体由相互交错的长柱状β—Si3N4晶粒组成.显微结构均匀。 相似文献
7.
利用Si3N4—SiC材料在冰晶石静态融盐电解质中的腐蚀实验研究材料的腐蚀性能,对腐蚀增重率进行记录分析,Si3N4的含量是影响材料腐蚀性能的重要因素,根据实验测定得出Si3N4的含量越高,Si3N4-SiC材料腐蚀程度越严重。 相似文献
8.
Ar,Ti离子注入Si3N4表面改性的研究 总被引:6,自引:0,他引:6
研究了Si3N4陶瓷及其表面蒸镀Al膜试样的离子注入效果,结果表明,Ti离子的注入与Ar离子的注入都可提高Al膜与陶瓷基体的结合力,并在一定的注入的剂量范围内随着注入剂量的增加,Al膜与陶瓷基体的结合力也有增加的趋势。Ti离子的注入使表面硬度增加,表面硬度随Ti离子注入量的增加而提高。Ar离子的注入(10^15Ions.cm^-2)也使表面硬度增加,但继续增加Ar离子的注入量,表面硬度却下降。根据 相似文献
9.
10.
11.
12.
Silicon - Nowadays, porous Si3N4 ceramics are fabricated by high purity α-Si3N4 powders, resulting in a higher cost of production. To reduce cost and save energy, in this research, high levels... 相似文献
13.
14.
采用无压烧结工艺制备了长柱状β-Si3N4品种.研究了晶种尺寸对Si3N4陶瓷力学性能和显微结构的影响.结果表明:在1750℃通过控制保温时间(1h、1.5h和2h)可获得不同尺寸的长柱状β-Si3N4晶种.Si3N4陶瓷加入晶种后,其相对密度和抗弯强度虽略有降低,但断裂韧性得到大幅提高.平均长度为4.51μm,长径比为5.71的品种对Si3N4陶瓷的增韧效果最佳;且随着其添加量的增加,Si3N4陶瓷的断裂韧性先升高再降低,当掺量为2wt%时断裂韧性达到最高(提高了20%以上).显微结构分析表明,Si3N4陶瓷断裂韧性的提高,与因晶种加入而导致的Si3N4晶粒长径比和大长柱状晶粒含量的增加有关. 相似文献
15.
《溶剂提取与离子交换》2013,31(5):631-643
Abstract The extraction behavior of U(VI), Np(V), Pu(IV), Am(III), and TcO4 ? with N,N,N′,N′‐tetraisobutyl‐3‐oxa‐glutaramide (TiBOGA) were investigated. An organic phase of 0.2 mol/L TiBOGA in 40/60% (V/V) 1‐octanol/kerosene showed good extractability for actinides (III, IV, V VI) and TcO4 ? from aqueous solutions of HNO3 (0.1 to 4 mol/L). At 25°C, the distribution ratio of the actinide ions (D An) generally increased as the concentration of HNO3 in the aqueous phase was increased from 0.1 to 4 mol/L, while the D Tc at first increased, then decreased, with a maximum of 3.0 at 2 mol/L HNO3. Based on the slope analysis of the dependence of D M (M=An or Tc) on the concentrations of reagents, the formula of extracted complexes were assumed to be UO2L2(NO3)2, NpO2L2(NO3), PuL(NO3)4, AmL3(NO3)3, and HL2(TcO4) where L=TiBOGA. The enthalpy and entropy of the corresponding extraction reactions, Δr H and Δr S, were calculated from the dependence of D on temperature in the range of 15–55°C. For U(VI), Np(V), Am(III) and TcO4 ?, the extraction reactions are enthalpy driven and disfavored by entropy (Δr H<0 and Δr S<0). In contrast, the extraction reaction of Pu(IV) is entropy driven and disfavored by enthalpy (Δr H>0 and Δr S>0). A test run with 0.2 mol/L TiBOGA in 40/60% 1‐octanol/kerosene was performed to separate actinides and TcO4 ? from a simulated acidic high‐level liquid waste (HLLW), using tracer amounts of 238U(VI), 237Np(V), 239Pu(IV), 241Am(III) and 99TcO4 ?. The distribution ratios of U(VI), Np(V), Pu(IV), Am(III) and TcO4 ? were 12.4, 3.9, 87, >1000 and 1.5, respectively, confirming that TiBOGA is a promising extractant for the separation of all actinides and TcO4 ? from acidic HLLW. It is noteworthy that the extractability of TiBOGA for Np(V) from acidic HLLW (D Np(V)=3.9) is much higher than that of many other extractants that have been studied for the separation of actinides from HLLW. 相似文献
16.
以三聚氰胺、三聚氯氰为原料,550℃热聚合法制备了g-C_3N_4(FCN)。~(13)CNMR、XRD证明该g-C_3N_4的结构单元是3-s-三嗪环,电镜照片显示FCN形貌为木耳状,边缘较厚。原料三聚氯氰、三聚氰胺分别是4 g和2 g时,N_2吸附-脱附测定FCN1的比表面积为156.25 m~2/g,孔径60 nm。UV-Vis漫反射测试FCN1的吸收边缘为482 nm,对应禁带宽度2.57 eV,PL光谱显示FCN1光致发光强度最弱。可见光照射下,30 mg FCN1加入30 mL(30 mg/L)的罗丹明B(RhB)溶液中,50 min后RhB的光降解率是99.62%,光催化剂循环实验表明该木耳状g-C_3N_4具有良好的稳定性。 相似文献
17.
18.
19.
20.
通过先使Si3N4陶瓷材料在1750℃、1MPa氮气压力下烧结,再在1950℃、7MPa氮气压力下烧结,从而获得高性能的Si3N4陶瓷材料,其抗弯强度为725MPa,断裂韧性为7.8MPa·m1/2. 相似文献