共查询到19条相似文献,搜索用时 187 毫秒
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本文利用爆炸式和电磁式加速器模拟研究空间粉尘粒子对高温热管的碰撞损伤效应.研究表明,微米级粉尘粒子难以击穿航天器高温热管管壁,但对热管表面的热控涂层光学性能变化有较大影响.亚毫米级粉尘粒子取决于速度的不同,高温热管由表面热控涂层光学性能下降一直到被击穿发生载热体的泄漏现象.针对高温热管在高速粉尘粒子撞击下的运行密封性和辐射功率等问题进行了试验研究及理论分析.测量结果表明,高温热管在工作温度T=900K时,被粉尘粒子击穿的速度由常温下的5.3 km/s降为4.8 km/s. 相似文献
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基于涂层性能退化的卫星红外辐射灵敏度分析 总被引:2,自引:1,他引:1
由于卫星表面热控涂层在空间恶劣环境下发生性能退化,导致实际参数与设计参数发生偏差,而重复计算卫星温度场和红外辐射耗时非常大.本文首先根据地面模拟实验数据建立了热控涂层性能退化模型,然后在卫星温度场和表面红外辐射计算模型的基础上,推导了卫星表面节点温度灵敏度和红外辐射灵敏度的计算公式.结合具体的卫星模型和轨道参数,求解了卫星表面节点温度灵敏度和红外辐射灵敏度.结果表明,热控涂层性能退化造成的卫星红外辐射特性变化,可直接利用卫星红外辐射灵敏度来分析,避免了卫星温度场和空间红外辐射的重复计算. 相似文献
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为了提高C/C复合材料的抗氧化性能,采用大气等离子喷涂(APS)法在C/C表面制备ZrO2/SiO2复合涂层,选用氧乙炔在1450,1700,2000℃下对涂层进行烧蚀考核,并对团聚粉体以及烧蚀前后涂层的成分及组织进行分析.结果 表明:大气等离子喷涂虽然可以实现C/C基体表面ZrO2/SiO2复合涂层的制备,但是由于2种材料熔点差异较大导致粉体熔融不充分,涂层孔隙率为40.12%,涂层结合强度为12.1 MPa.ZrO2/SiO2复合涂层抗烧蚀性能表现较好,其防护机理随温度的增加可以分为2个阶段:低温阶段,SiO2熔化并起到封填愈合作用,提高了致密度,ZrO2逐渐形成骨架,支撑液态SiO2;高温阶段,SiO2逐渐蒸发损耗,涂层中仅剩ZrO2并且发生烧结,继续起到抗氧化烧蚀的作用. 相似文献
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采用涂层刀具高速切削TC4(Ti6-Al4-V)时,其寿命短的问题较为突出.对涂层刀具进行表面后处理可大幅提高涂层刀具的表面完整性,是延长刀具寿命的有效途径.针对高速干切削钛合金的TiAlN涂层刀具,选用湿式微喷砂处理工艺进行表面后处理,分析微喷砂处理对涂层刀具表面微观形貌、表面粗糙度、表面显微硬度、表面残余应力的影响规律,并进行高速干切削试验,深入研究微喷砂处理对涂层刀具寿命及磨损机理的影响.结果表明:合适的微喷砂处理工艺(水料混合湿式微喷砂,喷砂压强为0. 1~0. 5 MPa,喷砂时间为0~10 s,喷砂颗粒为Al2 O3 或ZrO2 颗粒)可去除涂层初始表面大颗粒、凸起等缺陷,从而改善刀具的表面形貌,但过高的喷砂参数会在涂层刀面引入凹坑、微裂纹等,增大了其表面粗糙度值.喷砂颗粒、喷砂时间主要影响颗粒撞击涂层表面时对TiAlN涂层材料的去除量,改变涂层刀面的形貌、粗糙度与残余应力,喷砂压强主要影响颗粒的冲击力度,改变表面的硬度与残余压应力.与未处理刀具相比,处理后的涂层刀具的表面完整性提升显著,稳定磨损阶段持续时间延长,刀具寿命可提升50% ,微喷砂表面处理可广泛应用于各种涂层刀具表面处理. 相似文献
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激光熔敷钴合金涂层的抗空蚀和冲刷磨损性能 总被引:2,自引:0,他引:2
采用激光熔敷方法在20SiMn低合金钢表面制成了Co合金涂层,以两种目前水轮机转用材20SiMn低合金钢和0Cr13Ni5Mo不锈钢作为对比材料,对涂层进行了空蚀,液固两相流冲刷磨损及空蚀和冲刷磨损联合作用实验,采用失重法并结合能谱分析,X射线衍射分析及显微硬度测量等手段研究了涂层的显微结构和在不同形式损伤下涂层的性能并分析了原因。结果表明:在20SiMn低合金钢表面激光熔敷形成的Co合金涂层有良好的抗空蚀性能,这与涂层在空蚀过程中发生的应力诱发马氏体相变密切相关。良好的抗空蚀性能有利于提高涂层抗空蚀和冲刷磨损联合破坏,从而使涂层表现出与0Cr13Ni5Mo不锈钢接近的抗联合损伤性能。 相似文献
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Melninkaitis A Tolenis T Mažulė L Mirauskas J Sirutkaitis V Mangote B Fu X Zerrad M Gallais L Commandré M Kičas S Drazdys R 《Applied optics》2011,50(9):C188-C196
ZrO2-SiO2 and Nb2O5-SiO2 mixture coatings as well as those of pure zirconia (ZrO2), niobia (Nb2O5), and silica (SiO2) deposited by ion-beam sputtering were investigated. Refractive-index dispersions, bandgaps, and volumetric fractions of materials in mixed coatings were analyzed from spectrophotometric data. Optical scattering, surface roughness, nanostructure, and optical resistance were also studied. Zirconia-silica mixtures experience the transition from crystalline to amorphous phase by increasing the content of SiO2. This also results in reduced surface roughness. All niobia and silica coatings and their mixtures were amorphous. The obtained laser-induced damage thresholds in the subpicosecond range also correlates with respect to the silica content in both zirconia- and niobia-silica mixtures. 相似文献
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利用sol-gel方法合成了ZrO2薄膜,并通过在ZrO2薄膜中复合CdS纳米粒子成功地制备了ZrO2:CdS薄膜.制得的ZrO2薄膜透明并具有较好的光透射性,而ZrO2的含量及膜厚是影响其光透射性的主要因素.分散在ZrO2:CdS薄膜中的CdS纳米粒子为六方相结构,并具有较好的分散性,其平均尺寸为4~6nm.实验结果表明:ZrO2颗粒的晶化会对薄膜的光学性能及表面形貌产生影响,但CdS的形成可以抑制薄膜表面ZrO2颗粒的晶化,从而得到较为平滑的薄膜. 相似文献
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ZrO2涂层成分对其抗热腐蚀能力的影响 总被引:1,自引:0,他引:1
本文研究等离子喷涂不同成分ZrO_2涂层的抗热腐蚀能力。结果表明,熔盐热腐蚀过程表现为涂层表面的熔盐渗入内部和熔盐热分解产生的腐蚀气体向涂层内部扩散两个方面。在ZrO_2中添加适量的SiO_2,可显著提高涂层的抗热腐蚀能力。Y_2O_3稳定ZrO_2的效果比CaO好,因为在相同热腐蚀条件下,CaO与熔盐反应,使ZrO_2从四方相转变为单斜相。 相似文献
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以WC,ZrO2,Cr2O3和Al2O3陶瓷颗粒为增强相,镍合金粉末为基体,运用等离子喷涂技术制备四种陶瓷/镍合金复合涂层。采用冲蚀磨损试验机和正交试验方法,进行陶瓷颗粒相浓度、磨粒粒度、冲蚀角和速度对陶瓷颗粒/镍合金复合涂层抗冲蚀磨损性能影响的试验研究。采用表面形状测量仪对陶瓷颗粒/镍合金复合涂层磨损表面形貌进行测量和分析。试验结果得到WC,ZrO2,Cr2O3和Al2O3四种陶瓷颗粒/镍合金复合涂层冲蚀磨损率的经验关联式。 相似文献
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Mukesh Kumar 《Bulletin of Materials Science》2009,32(4):459-462
The scattering from moisture rough surface with spheroidal dust particles having surface with spheroidal dust particles has
recently received much attention. In part due to the recent prediction and observation of the spheroidal dust particles in
rough surfaces under elastic wave by the Kirchhoff scattering model and scalar approximation with slope. Our analysis shows
that the scattering depends on the moisture (2–4·5%) with spheroidal dust particles. At slightly moisture rough surface the
dielectric properties increase with change in field amplitude in a rough surface with spheroidal dust particles. 相似文献
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《材料科学技术学报》2016,(3)
A new type of transparent scratch resistant coatings including in-situ modified SiO_2(g-SiO_2) in flame spray pyrolysis(FSP) process was prepared. The maximum content of g-SiO_2 in the coating was 15 wt%, which is higher than that of SiO_2 modified by traditional wet chemical route(l-SiO_2, only 10 wt%). The results of transmission electron microscopy have demonstrated that in-situ surface modified g-SiO_2 particles dispersed well with smaller agglomerates in the final coating, which was much better than the particles modified via wet chemical route. Visible light transmittance and haze tests were introduced to characterize the optical quality of the films. All coatings were highly transparent with the visible light transmittance of above 80%, especially for coatings containing g-SiO_2, which exhibited slightly higher visible light transmittance than l-SiO_2 embedded one. The haze value of coatings incorporated with 15wt% g-SiO_2 was 1.85%, even lower than the coating with 5 wt% l-SiO_2(haze value of 2.09%), indicating much better clarity of g-SiO_2. The excellent optical property of g-SiO_2 filled coatings was attributed to the good dispersion and distribution of particles. Nano-indention and nano-scratch tests were conducted to investigate the scratch resistance of coatings on nano-scale. The surface hardness of the coatings rose by 18% and 14%, and the average friction coefficient decreased by 15% and 11%, respectively, compared to the neat coat due to the addition of 10 wt% g-SiO_2 and l-SiO_2. The pencil hardness of the coating with 15 wt% g-SiO_2 increased from 2B for the neat coating to 2H. However, the pencil hardness of coating with 10 wt% l-SiO_2 was only H. The results showed that the g-SiO_2 embedded coatings exhibited higher scratch resistance and better optical properties. 相似文献
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等离子喷涂制备HA/ZrO2复合涂层 总被引:2,自引:0,他引:2
采用等离子喷涂技术,在Ti-6Al-4V基体上成功地制备了羟基磷灰石/氧化锆(HA/ZrO2)复合涂层,对涂层的微观结构、相组成和结合强度进行了研究,并以模拟体液试验评估涂层的生物活性.结果表明,复合涂层具有较为均匀的微观结构.HA/ZrO2复合涂层的结合强度明显高于 HA涂层, HA/60 wt% ZrO2涂层的结合强度高达 28.5MPa,为 HA涂层的 2.2倍.复合涂层在模拟体液中浸泡一段时间后,表面覆盖一层碳酸磷灰石(carbonate-apatite),表明涂层具有良好的生物活性. 相似文献
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Plasma spraying of zirconia-reinforced hydroxyapatite composite coatings on titanium: Part I Phase, microstructure and bonding strength 总被引:4,自引:0,他引:4
Chang E Chang WJ Wang BC Yang CY 《Journal of materials science. Materials in medicine》1997,8(4):193-200
Plasma-sprayed hydroxyapatite (HA) coatings applied to metal substrates can induce a direct chemical bond with bone and hence achieve biological fixation of the implant. However, the poor bonding strength between HA and substrate has been of concern to orthopaedists. In this study, two submicrometre ZrO2 powders stabilized with both 3 and 8 mol% Y2O3 (TZ3Y and TZ8Y, respectively) were incorporated in a plasma-sprayed HA coating on Ti-6Al-4V substrate to investigate the change in phase, microstructure and bonding strength. The results show that ZrO2 composite coatings contain more unmelted particles and greater porosity. During plasma spraying, ZrO2 reacts with the CaO in HA to form CaZrO3 and accelerates HA decomposition to -TCP and Ca4P2O9. Nevertheless, bonding strength increases with increase of ZrO2 content in the range 0 to 10 wt% studied. The higher Y2O3-containing TZ8Y apparently exerts a greater strengthening effect than the lower Y2O3-containing TZ3Y. 相似文献
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采用接枝聚合反应在纳米ZrO2表面接枝聚对苯二甲酸乙二醇酯 (PET) 低聚物,以提高其与聚碳酸酯(PC)的相容性;改性纳米ZrO2与PC经过共混挤出,制备了纳米ZrO2/PC复合材料。采用FTIR、XPS、TEM、TG、接触角等测试方法对接枝改性后的纳米ZrO2进行了表征,结果表明,PET化学键合到了纳米ZrO2表面,使ZrO2疏水性显著增强,微观颗粒分散性好。对纳米ZrO2/PC复合材料进行了力学性能测试,探讨了纳米ZrO2的添加量与复合材料力学性能的关系。结果表明:纳米ZrO2/PC复合材料的力学性能较纯PC有明显改善;随着改性纳米ZrO2含量的增加,缺口冲击强度和拉伸强度都呈现出先增加后降低的趋势,分别在ZrO2质量分数为1%和0.3%时达到最大值;弯曲强度在实验范围内一直呈上升趋势,最大弯曲强度比纯PC提高2.54 MPa。 相似文献