严友兰
,
余娟丽
,
张健
,
张大海
,
王红洁
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2010.02.016
利用凝胶注模成型工艺,在固定单体交联荆总质量的情况下,改变单体与交联剂的质量比例,制备出不同单体与交联剂比例的多孔氮化硅陶瓷.借助扫描电子显微镜、Archimedes法和三点弯曲法等方法研究了单体与交联剂比例对多孔氮化硅陶瓷的微观结构和基本力学性能的影响.结果表明,随着单体与交联剂比例的增大,试样的干燥收缩率增大;当单体与交联剂比例≥15时,试样排胶后出现开裂现象;当单体与交联剂比例<15时,随着单体与交联剂比例增大,烧成后的试样强度呈增大的趋势.
关键词:
凝胶注模
,
排胶
,
比例
,
氮化硅
,
显微结构
Ruihua HU
,
Montasser M.Dewidar
,
Hyo-Jin KIM
,
Jae-Kyoo LIM
,
null
材料科学技术（英文）
In order to improve the wear resistance of Ti-6Al-4V, different amounts of Si3N4 powder were added into the alloy powder and sintered at 1250℃. Porous titanium alloy with higher wear resistance was successfully fabricated. At sintering temperature, reaction took place and a new hard phase of Ti5Si3 formed. The mechanical properties of the fabricated alloys with different amounts of Si3N4 addition were investigated. The hardness of Ti-6Al-4V, which is the index of wear resistance, was increased by the addition of Si3N4. Amounts of Si3N4 addition have very significant influences on hardness and compressive strength. In present study, titanium alloy with 5 wt pct Si3N4 addition has 62% microhardness and 45% overall bulk hardness increase, respectively. In contrast, it has a 16.4% strength reduction. Wear resistance was evaluated by the weight loss during wear test. A new phase of Ti5Si3 was detected by electron probe microanalyzer (EPMA) and X-ray diffraction (XRD) method. The original Si3N4 decomposed during sintering and transformed into titanium silicide. Porous structure was achieved due to the sintering reaction.
关键词:
Ti-6Al-4V
,
alloy
,
Wear
,
Sintering
,
reaction
Wen ZHANG
材料科学技术（英文）
Macroporous silicon nitride (Si3N4) ceramics with high strength, uniform structure and relatively high porosity were obtained by gelcasting and carbonthermal reaction in a two-step sintering technique. Microstructure and composition were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD). Open porosity, pore size distribution and basic mechanical performance were measured by Archimedes method, mercury intrusion porosimetry and three-point bending methods, respectively. SEM and TEM results revealed that pores were formed by elongated β-Si3N4. SADP measurement proved the formation of SiC particles. The SiC granules were beneficial for the formation of high ratio elongatedβ-Si3N4, and at proper amount, they also acted as reinforcement phase. Thermodynamic analysis indicated that the mechanisms of the reactions were mainly associated with liquid-solid reaction and gas-liquid reaction.
关键词:
Ceramics
,
null
,
null
,
null
H.Huang
,
X.Z.Hu
,
Y.Liu
,
M.Bush
,
K.Winchester
,
C.Musca
,
J.Dell
,
L.Faraone
材料科学技术（英文）
An experimental investigation of mechanical properties of thin films using nanoindentation was reported. Silicon nitride thin films with different thicknesses were deposited using plasma enhanced chemical vapor deposition (PECVD) on Si substrate. Nanoindentation was used to measure their elastic modulus and hardness. The results indicated that for a film/substrate bilayer system, the measured mechanical properties are significantly affected by the substrate properties. Empirical formulas were proposed for deconvoluting the film properties from the measured bilayer properties.
关键词:
Mechanical property
,
null
,
null
,
null
