C／C复合材料Mo-Si-N抗氧化涂层的制备

在C／C复合材料表面采用熔浆法制备Mo—Si系涂层的烧结过程中通入氮气，开发了Si3N4．MoSi2／Si—SiC（Mo-Si-N系）多层抗氧化涂层，并初步考察了涂层的抗氧化性能。结果表明，多层涂层的致密性主要受制于起始氮化温度。只有在Si熔点以上通入氮气，才能获得致密无缺陷的涂层。多层涂层的底层为SiC，外层为Si3N4，中间层为MoSi2／Si。这种多层涂层的抗氧化性能与涂层中MoSi2的含量有关；MoSi2含量为30％（体积分数，下同）和40％时，与真空中合成的Mo-Si涂层相比，高温抗氧化性能显著改善，抗氧化温度提高到1400℃～1450℃。     

ZrB2-MoSi2/SiC涂层C/C复合材料的制备及氧化性能（英文）

为了提高C/C复合材料的抗氧化性,在C/C复合材料基体上制备了ZrB2-MoSi2/SiC涂层。采用包埋法制备SiC中间层,采用喷涂法制备ZrB2-MoSi2外涂层。用XRD和SEM分别分析、测试所制备涂层的物相组成和显微结构,研究涂层复合材料的高温抗氧化性能。结果表明:C/C复合材料的外涂层由ZrB2、MoSi2和SiC三相组成;在1273K和1773K下分别氧化30h和10h后ZrB2-MoSi2/SiC涂层试样的质量损失分别为5.3%和3.0%,涂层表面长有纳米SiC晶须。C/C复合材料ZrB2-MoSi2/SiC涂层具有自愈合特性和良好的高温抗氧化性能。     

SiC/Si-MoSi2/MoSi2涂层的抗氧化性能

用液硅渗透和料浆烧结法在石墨基体上制备了SiC/Si-MoSi2/MoSi2抗氧化涂层,并研究了涂层的组织结构以及抗氧化性能.结果表明涂层结构由内到外依次为SiC内层、Si和MoSi2组成的中间过渡层、MoSi2外层,呈现出良好的梯度分布特征.涂层在1700℃的高温下具有极好的抗氧化性能和抗热震性能.     

镍基合金表面二硅化钼复合涂层的制备和性能

为了改善K403镍基高温合金的高温抗氧化性能,采用大气等离子喷涂在镍基合金表面制备了4种不同结构的MoSi2复合涂层。结果表明:4种结构涂层中K403/NiCoCrAlY/ZrO2/30%(体积分数)ZrO2-MoSi2/MoSi2复合涂层的抗热震性能最好,且该涂层的界面结合强度最高(22.5 MPa)。MoSi2涂层的自身结合强度大于涂层界面结合强度,结合机理以机械咬合式为主。该复合涂层在1 200℃氧化120 h后的质量增加仅为3.42 mg/cm2,提高K403合金和传统氧化锆涂层的抗氧化性能。MoSi2复合涂层表面在高温时生成了一层致密的SiO2保护膜,阻碍了氧的扩散,减轻了过渡层NiCoCrAlY/ZrO2界面处的氧化。     

SiC/MoSi2高温抗氧化涂层的制备及性能探究

采用磁控溅射法在C/C复合材料表面制备SiC/MoSi2抗氧化涂层,并利用SEM、XRD以及EDS等测试手段对涂层的组织结构、抗氧化性能以及抗氧化机制进行了研究。结果表明,所得涂层结构致密、厚度均匀可控,呈柱状晶。在1500℃静态氧化60min后,涂层试样表现出了较优异的抗氧化性能,氧化质量损失仅为3.2x10-2g/cm-2。导致C/C基体被氧化失重的主要原因是涂层中沿晶界产生的贯穿裂纹为氧气进入基体表面提供了通道。     

MOSi2涂层的组织结构与高温抗氧化性能

采用包渗法在Nb-10W合金基体上制备MoSi2涂层,测试了涂层试样的1 600℃静态抗氧化和室温至1 600℃循环抗氧化性能,分析了硅化过程中涂层的形成机理、涂层表面和截面的形貌以及氧化后涂层成分与结构变化。采用包渗法制备的硅化物涂层是通过反应扩散形成的,该涂层为复合结构:MoSi2相主体层;以NbSi2相为主、并含少量Nb5Si3相的两相过渡区;Nb5Si3相扩散层;该涂层结构表现出良好的高温抗氧化和抗热震性能;Si的扩散是通过空位的反应流动实现的,空位在主体层与两相过渡区界面处聚集成微孔带,氧化后微孔带宽度增加;致密的低硅化物扩散层能有效地阻止裂纹向基体扩展。     

SiC涂层对泡沫炭高温抗氧化性能的影响

采用包埋法在中间相沥青基泡沫炭表面生成了一层致密的高温抗氧化碳化硅涂层,研究了SiC涂层对泡沫炭高温抗氧化性能的影响.通过热重分析仪(TG)对有、无SiC涂层的泡沫炭的抗氧化性能变化进行了分析,采用扫描电子显微镜(SEM)分析了SiC涂层的结构和形貌特征变化,同时在1 200℃空气气氛中对SiC涂层的抗氧化性能进行了测试.结果表明:SiC涂层使泡沫炭的抗氧化性能有了显著的提高,并且随着SiC涂层厚度的增加,泡沫炭的抗氧化性能也随之增强.     

铌表面MoSi2高温涂层的形貌和结构研究

用料浆熔烧法在铌基体表面制备了。MoSi2高温抗氧化涂层。利用SEM，EDS，XRD等仪器分析研究了涂层的结构、元素分布、相分布与抗氧化性能的关系。结果表明：涂层与基体之间达到了冶金结合，通过扩散形成了过渡层，涂层的复合结构有利于提高抗氧化性能，用料浆熔烧法在铌基体表面制备MoSi2涂层是可行的。在氧化环境下，MoSi2涂层能在表面自生成一层SiO2玻璃层，阻止氧的进一步扩散。经2h以上高温氧化后，Si的扩散使涂层主体中形成多孔疏松组织。涂层元素与基体发生互扩散，在界面处形成大量集中孔洞并横向贯穿，使涂层从其主体与过渡层接触的界面处发生横向内部断裂，导致涂层失效。     

包埋渗结合激光熔覆制备复合涂层的高温抗氧化性

为了提高铌合金的抗氧化性能,采用铝硅共渗的方法在铌合金表面制备Al-Si涂层,结合激光熔覆技术于渗层上熔覆MOSi2涂层。探讨了Al-Si渗层的生长机制,研究了铌合金表面Al-Si渗层及MoSi2/Al-Si涂层的抗高温氧化性能。结果表明:Al-Si渗层的形成过程是源于Al、Si元素的先后沉积,优先形成了Al3Nb相。渗层厚度x与保温时间f遵循关系式:x=At1/2+7.4(1000℃:A=11.6,1050℃:A=16.2)。激光熔覆制备的MoSi2/Al-Si涂层均匀连续致密,与基体结合紧密,无裂纹孔洞等缺陷。主要相结构为MoSi2、Al3Nb、NbSi2、Nb5Si3和Mo(Si,Al)2。经1200℃氧化后,Al-Si渗层及MoSi2/Al-Si涂层都形成大量的SiO2保护膜,阻止了氧原子的进一步扩散。与Al-Si渗层相比,MoSi2层表面形成的连续致密混合氧化物有效避免了Al-Si渗层的快速消耗,MoSi2/Al-Si涂层的高温氧化优于Al-Si渗层。     

磁控溅射法制备碳/碳复合材料 SiC/MoSi2-ZrB2 涂层的结构及抗氧化性能研究

通过磁控溅射法在碳/碳复合材料表面成功制得了SiC/MoSi2-ZrB2陶瓷涂层并对结构及其在高温有氧环境中的抗氧化性能进行了研究。结果表明制备的SiC/MoSi2-ZrB2陶瓷涂层呈柱状晶结构且均匀性良好,其在1273K和1773K的有氧环境中氧化60min失重率分别是5.6×10-2 g/cm2 和 6.3×10-2 g/cm2。     

金属钼表面Mo-C-N-Si涂层的制备及其高温氧化特性

在金属钼表面制备了Mo-C-N-Si涂层,研究了涂层在1600℃大气环境下的氧化特性,采用SEM和XRD分析了涂层的微观结构和物相组成。结果表明:Mo-C-N-Si涂层以MoSi2为主相,SiC和Si3N4为次相,存在Mo2C+MoxN中间层;由于扩散和氧化反应,涂层在氧化初期形成SiO2氧化膜层、MoSi2主体层、Mo5Si3层和Mo2C+MoxN层等四层结构,氧化后期转变为Mo2C+MoxN层和Mo3Si+Mo5Si3层的双层结构,导致涂层失效。由于C、N的引入,涂层抗热震性能良好。     

Thermal Fatigue Behavior of SiC/MBAS Glass Coated Carbon/Carbon Composites

The thermal fatigue behavior of C/C composites coated with the SiC/MBAS glass (MoSi2 particle-containing boron aluminosilicate glass) coating, prepared by the two-step process of the pack cementation and procoating-sintering, was investigated in present paper. The experimental results indicated that the SiC/MBAS glass coating had an excellent thermal shock resistance in air at temperature up to 1873 K. During quick thermal cycle between 1873K and room temperature in air, the decrease of mass and mechanical ...     

MoSi2 oxidation resistance coatings for Mo5Si3/MoSi2 composites

In order to improve the oxidation resistance properties of 30 at.% Mo5Si3/MoSi2 composite at high temperature in air, a molybdenum disili-tide coating was prepared on its surface by a molten salt technology. XRD and SEM analysis showed that only tetragonal MoSi2 phase ex-isted in the coating after being siliconized for 5 h at 900℃. The oxidation film formed on the uncoated sample was not dense, so that oxygen diffused easily through it. The volatilization of MoO3 resulted in the oxidation film separating from the substrate. The MoSi2coating was proved to be an effective method to prevent 30 at.% MosSi3/MoSi2 composites from being oxidized at 1200℃. A dense glassy SiO2 film was formed on the MoSi2 coating surface, which acted as a barrier layer for the diffusion of oxygen atoms to the substrate. The 30at.% Mo5Si3/MoSi2 composites with a MoSi2 coating showed much better oxidation resistance at high temperature.     

Effect of Thermal Shock and Oxidation on Mechanical Property of Carbon/Carbon Composites with a Silicide Coating

A SiC whisker-toughened MoSi2-SiC-Si coating was prepared on carbon/carbon (C/C) composites surface by a two-step technique of slurry and pack cementation, and the effects of thermal shock and oxidation on the mechanical property of the coated C/C were studied. The flexural strength of C/C composites was improved by 6.8% after coated by SiC whisker-toughened MoSi2-SiC-Si. After thermal cycle between 1773 K and room temperature in air for 10 times, the mass loss of the coated sample was 5.08% and the percent...     

Effect of Mo/Si Ratio on the Microstructure and Oxidation Resistance of Si-Mo Coating for C/C Composites

Oxidation protective Si-Mo coatings were prepared by pack cementation on the surface of C/SiC coated carbon/carbon composites. The influences of Mo/Si mass ratio in the pack powders on the microstructure and oxidation resistance of the coating were investigated. It showed that with the Mo/Si ratio increasing from 0.1 to 0.4, the MoSi2 proportion and the dimension of cracks in the coating increased, and the oxidation protective ability of the coated specimens firstly increased and then decreased. The coating...     

硅化钽/硅化钼基热防护涂层短时高温结构演化

以硅化钽、硅化钼、硼硅玻璃粉为原料,1200℃短时烧结制备了耐高温热防护涂层。然后采用乙炔焰在1650℃烧蚀涂层2 min,自然冷却至室温。利用X射线衍射、扫描电子显微镜和X射线电子能谱研究了该耐高温热防护涂层在1650℃加热前后的涂层结构和组分变化。结果显示制备出的热防护涂层表面为Ta2O5和少量TaSi2。经过1650℃短时高温烧蚀后,涂层表面烧蚀中心区形成大量片状Ta2O5,该Ta2O5连成片。涂层截面形貌显示高温烧蚀后涂层接近表面部分发生致密化,厚度约23μm。涂层截面的元素面扫描分析显示截面上钽、钼元素分布均匀,即涂层具有良好的结构均匀性。     

Microstructure of a Mo-Si-C-N multi-layered anti-oxidation coating on carbon/carbon composites by fused slurry

A Mo-Si-C-N multi-layered anti-oxidation coating was in-situ fabricated by introducing nitrogen atmosphere during the fused sintering of Mo-Si slurry pre-layer on carbon/carbon composites. The phase composition and microstructure of the Mo-Si-C-N coating were character-ized by X-ray diffractometry, optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The Mo-Si-C-N coating exhibited a three-layered structure. Besides the MoSi2/Si main-layer and the SiC bonding-layer, a surface layer of about 10 μm in thickness was synthesized on the coating surface. The surface layer mainly consisted of SiC nanowires and contained some Si3N4 and Si phases. SiC nanowires of 10 to 200 nm in diameter presented a terrace and distortion structure. Transmission electron microscopy indicated that the SiC nanowires grew along the preferred <111> direction. Dur-ing oxidation test, SiC nanowires transmuted into Sit2 glass, which can play an important role in improving the oxidation resistance of C/C composites.     

钼合金Si-Cr-Ti-SiC-MnO2涂层的制备与组织性能

目的提高钼合金表面红外辐射性能与高温抗氧化性能。方法将40%Si、20%Cr、5%Ti、5%SiC、30%Mn O_2五种粉末与酒精、粘结剂按比例混合,经高能球磨6 h后制得均匀悬浮的料浆。采用浸涂工艺对预处理的钼合金试样进行料浆涂覆,在1450℃真空烧结0.5 h后制得黑色涂层试样。通过1550℃高温静态氧化试验和高温粒子薄片红外光谱综合实验系统,分别评价涂层抗氧化性能和红外辐射性能,并通过扫描电镜(SEM)、能谱分析(EDS)、X射线衍射仪(XRD)对涂层氧化前后的形貌与组织结构进行分析。结果钼合金Si-Cr-Ti-SiC-Mn O_2涂层在700、900℃的法向发射率分别达0.85、0.88,在1550℃高温有氧环境下的静态抗氧化寿命达7 h。原始涂层呈四层复合梯度结构,由外到内分别为SiO_2+Mn3O_4+M5Si3(M指Mo、Cr、Ti)、M5Si3+Mo Si2+SiC+Mn3O_4、Mo Si2、Mo5Si3。高温氧化后,涂层四层复合结构由外到内转变为SiO_2+(Cr,Ti)5Si3+Mn Cr2O_4+Mn3O_4、M5Si3+SiC+Mn Cr2O_4+Mn3O_4、Mo Si2、M5Si3。高温氧化过程中,MSi2高硅化物层逐渐转变为M5Si3低硅化物层,涂层表面形成含Mn Cr2O_4尖晶石相和复合硅化物的致密SiO_2玻璃膜。结论 Si-Cr-Ti-SiC-Mn O_2涂层可有效提高钼合金基体的红外辐射性能和高温抗氧化性能,复合硅化物与硅锰复杂氧化物具有良好的抗氧化性能、高辐射性能和自愈合性能。