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等离子喷涂纳米复合陶瓷涂层的组织结构及其形成机理 总被引:7,自引:0,他引:7
以Al2O3-13%TiO2(质量分数)团聚体复合陶瓷粉末为材料,采用等离子喷涂工艺在TiAl合金表面制备纳米结构陶瓷涂层.用扫描电镜(SEM)和X射线衍射仪(XRD)分析粉末和涂层形貌、微观结构及相组成,讨论涂层的微观组织形成机理.结果表明:纳米结构复合陶瓷涂层由部分熔化区以及与常规等离子喷涂类似的片层状完全熔化区组成;根据组织结构的不同,部分熔化区又分为液相烧结区(亚微米Al2O3粒子镶嵌在TiO2基质相的三维网状或骨骼状结构)和固相烧结区(经过一定程度长大但仍保持在纳米尺度的残留纳米粒子);等离子喷涂使部分α-Al2O3以及全部θ-Al2O3转变为亚稳态γ-Al2O3;纳米结构复合陶瓷涂层中的完全熔化区、液相烧结区及固相烧结区分别由等离子喷涂过程中纳米团聚体粉末中温度高于Al2O3熔点、介于TiO2熔点到Al2O3熔点之间以及低于TiO2熔点区域沉积获得,纳米结构涂层中不同部分熔化组织源于复合陶瓷粉末中Al2O3与TiO2之间的熔点差异. 相似文献
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以常规和纳米团聚体Al2O3-13TiO2(ω/%,下同)复合陶瓷粉末为原料,采用等离子喷涂工艺在TiAl合金表面制备常规和纳米结构陶瓷涂层.用扫描电镜(SEM)和X射线衍射(XRD)仪分析粉末和涂层形貌、微观结构及相组成,同时对纳米结构涂层的微观组织形成机制进行了讨论.结果表明:常规复合陶瓷涂层呈典型的等离子喷涂层状堆积特征;纳米结构复合陶瓷涂层由部分熔化区以及与常规等离子喷涂类似的片层状完全熔化区组成.根据组织结构的不同,部分熔化区又分为亚微米A12O3粒子镶嵌在TiO2基质相的三维网状或骨骼状结构的液相烧结区和经过一定长大但仍保持在纳米尺度的残留纳米粒子的固相烧结区,不同的部分熔化组织源于复合陶瓷粉末中A12O3与TiO2之间的熔点差异.由于等离子喷涂过程中涂层沉积时的快速凝固作用,不管是常规还是纳米涂层都以亚稳相γ-A12O3为主. 相似文献
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目的研究等离子喷涂纳米Al2O3-13%TiO2的特征喷涂参数(CPSP)对涂层微观结构及耐磨性能的影响,探索更合理的等离子喷涂工艺参数。方法采用等离子喷涂,在Q235钢表面制备过渡层为NiCrAl、陶瓷层为纳米Al2O3-13%TiO2的涂层系统。对涂层试样进行高温和常温磨损性能测试,并对比分析喷涂粉末、涂层的微观结构和相组成。结果纳米涂层为微观双模结构,由部分熔化区和完全熔化区组成,存在裂纹、孔隙等缺陷,其主要物相为α-Al2O3,γ-Al2O3和rutile-TiO2。纳米涂层磨损失效的主要原因是内部板条的分层剥落和涂层表面材料的塑性变形切削。结论随着CPSP的增大,纳米涂层的耐磨性能增强,且高温磨损性能较室温磨损性能为差。纳米Al2O3-13%TiO2涂层微观结构中部分熔化区结构和纳米晶粒的存在显著提高了涂层的耐磨性。 相似文献
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采用等离子喷涂设备在H13热作模具钢表面制备含有不同质量分数TiO2的Al2O3纳米陶瓷复合涂层。采用X射线衍射仪(XRD)、高温氧化试验、热震试验等手段研究等离子喷涂纳米涂层的相组成及其性能。结果表明,等离子喷涂使α-Al2O3转变为亚稳态的γ-Al2O3相,喷涂后涂层中Al2O3由α-Al2O3相和γ-Al2O3相组成,TiO2仍以金红石相存在。纳米AT20涂层比其他涂层具有更好的抗氧化性能;与其他涂层相比,纳米AT13涂层具有最佳的抗热震性能。 相似文献
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激光重熔改性等离子喷涂陶瓷涂层的组织及其耐腐蚀性能 总被引:23,自引:0,他引:23
以纳米Al2O3粉末为填料,采用激光重熔等离子喷涂陶瓷涂层技术,在45号钢表面制备了纳米改性Al2O3 13%(质量分数)TiO2/nano-Al2O3复合陶瓷涂层.用X射线衍射仪、扫描电镜研究了纳米Al2O3改性后的陶瓷涂层的组织及涂层的耐腐蚀性能.结果表明,在激光的作用下,原等离子喷涂层Al2O3 13%TiO2的片层状组织得以消除;激光重熔区亚稳相y-Al2O3转变为稳定相α-Al2O3,重熔层由α-Al2O3和TiO2组成.与等离子喷涂Al2O3及Al2O3 13%TiO2陶瓷涂层相比,纳米Al2O3改性后的Al2O3 13%TiO2/nano-Al2O3陶瓷涂层致密化程度明显提高,耐腐蚀性能也得到了明显的改善. 相似文献
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激光重熔纳米Al2O3-13%TiO2陶瓷涂层组织及性能 总被引:2,自引:0,他引:2
为了进一步提高等离子喷涂纳米Al2O3-13%TiO2(质量分数, 下同)复合陶瓷涂层的性能,在γ-TiAl基体材料表面采用激光重熔工艺对涂层进行处理,研究了激光重熔对涂层微观组织和性能的影响.用扫描电镜(SEM)和显微硬度计分析了涂层形貌、微观结构和显微硬度,同时对涂层的磨损特性进行了考察.结果表明,等离子喷涂纳米陶瓷涂层由纳米颗粒完全熔化区和部分熔化区两部分组成,仍然具有等离子喷涂态的典型层状结构.经过激光重熔后,形成了致密细小的等轴晶重熔区、烧结区和残余等离子喷涂区,由于激光快速加热和快速冷却加工特点,在重熔区仍保留了部分来源于原等离子喷涂部分熔化区的残留纳米粒子.与常规等离子喷涂陶瓷涂层相比,纳米结构涂层可在一定程度上提高其硬度和耐磨性,经过激光重熔后其硬度和耐磨性进一步提高. 相似文献
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TiAl合金表面激光重熔纳米陶瓷涂层 总被引:3,自引:0,他引:3
采用等离子喷涂和激光重熔复合工艺在TiA l合金表面制备了纳米A l2O3-13wt%TiO2复合陶瓷涂层。为了使重熔后的陶瓷涂层保留一定的纳米结构组织,采用相对较低的激光功率和能量密度进行重熔。用扫描电镜(SEM)和X射线衍射仪(XRD)分析了涂层形貌、微观结构和相组成。结果表明,等离子喷涂纳米陶瓷涂层由纳米颗粒完全熔化区和部分熔化区两部分组成,具有等离子喷涂态的典型层状结构;由于受到激光功率、能量密度、陶瓷材料热物性参数和涂层厚度等因素的综合影响,重熔后陶瓷涂层出现了明显的分层结构特征;依据组织形态的不同,可将其大致分为:重熔区、烧结区和残余等离子喷涂区。重熔区由致密细小的等轴晶组成,并且保留了部分来源于原等离子喷涂部分熔化区的残留纳米粒子。由于等离子喷涂过程中涂层沉积时的快速凝固作用,涂层以亚稳相-γA l2O3为主,经过激光重熔处理后,-γA l2O3又重新转变为稳定相-αA l2O3。 相似文献
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喷涂参数对Al2O3-13wt% TiO2纳米涂层组织和性能的影响 总被引:2,自引:1,他引:1
研究了等离子喷涂特征参数(CPSP)对Al2O3-13wt%TiO2纳米涂层相组成、微观组织和性能的影响.结果表明,纳米涂层含有αAl2O3、γ-Al2O3和金红石结构TiO2,其微观组织由全熔柱状晶区域和纳米结构的部分熔化区域组成.部分熔化区形貌与CPSP有关,低CPSP时主要为球状和部分条状,高CPSP条件下基本上都是不规则条状或块状.随CPSP增加,纳米涂层的结构缺陷减少,致密度提高.不同CPSP获得的纳米涂层的显微硬度和韧性均高于传统涂层,但CPSP过低或过高时,涂层中结构缺陷或结晶相较多,导致硬度和韧性降低.纳米涂层的耐磨性也随CPSP的变化而改变,并与涂层的组织、硬度和韧性的变化相对应. 相似文献
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M. Hoch 《Journal of Phase Equilibria and Diffusion》1996,17(4):290-301
We applied our model to the enthalpy of mixing data of the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen
ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates.
The same applies to the CaO-SiO2, CaO-Al2O3, PbO-B2O3, PbO-SiO2, ZnO-B2O3, and ZnO-SiO2 systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure
of the liquid.
Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of
the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct
solid-solid calorimetry. 相似文献
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The new phases KFe2(SeO2OH)(SeO3)3 and SrCo2(SeO2OH)2(SeO3)2 have been synthesized under low-hydrothermal conditions and their structures were determined by single-crystal X-ray methods. Both compounds are monoclinic; KFe2(SeO2OH)(SeO3)3: space group P2, A = 9.983(4), B = 5.270(1), C = 10.614(4) Å, β = 97.42(2)°, V = 553.7 Å3, Z = 2; SrCo2(SeO2OH)2(SeO3)2: space group P2ln, A = 14.984(2), B = 5.286(1), C = 13.790(2) Å, β = 94.72(1)°, V = 1088.5 Å3 , Z = 4. The refinements converged to R-values of 2.9 and 3.6% respectively.
The atomic arrangement in KFe2(SeO2OH)(SeO3)3 and SrCo2(SeO2OH)2(SeO3)2 is based on isolated MO6 octahedra (M = Fe3+, Co2+), which are corner-linked via trigonal pyramidal selenite groups to a framework structure. Interstitials are occupied by potassium or strontium atoms in ten- or eight-coordination respectively, and by the lone-pair electrons of the Se4+ atoms. Both compounds are not isotypic but are closely related and may be interpreted as different distortions of an idealized structure type in space group P2/m, which was modelled for a theoretical compound SrFe2(SeO3)4 by distance least squares refinement (program ). 相似文献
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Zhong-jia Huang 《Surface & coatings technology》2008,202(14):3208-3214
The MoS2 powders were coated with Al2O3 (5 wt.%) through controlling hydrolysis of Al (NO3)3·9H2O. MoS2 powder coated with Al2O3 was written as MoS2/Al2O3 hereinafter. MoS2/Al2O3 powders were put into Ni plating electrolyte bath. Cetyltrimethylammonium bromide (CTAB) — the surfactant was also put into the bath. The experiment proves that MoS2/Al2O3 particles were absorbed onto the Ni plate. The amount of MoS2/Al2O3 deposited on Ni plate rises with the increasing concentration of MoS2/Al2O3 in the bath. The microhardness, micro-surface, phase and the tribological property of the MoS2/Al2O3 multi-plating coating were measured and analyzed. The performances of microhardness and wear resistance of the Ni-MoS2/Al2O3 composite are better than those of Ni-MoS2 composite. 相似文献
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Wang Haiping Lu Tiecheng Wang Xuemin Ge Fangfang Cao Linhong Zhang Hongliang Li Chunhong Yu Xiaohan Ju Xin Wu Weidong 《Corrosion Science》2011,(3):1115-1119
LiBH4 films were prepared by pulsed laser deposition using a LiB target in a background pressure of hydrogen. The corrosion characteristics of LiBH4 films were measured by exposing them to a gas mixture of CO2/H2O/O2/N2 at ambient temperature for 1–24 h. Scanning electron microscopy images show some cracks on the surface of corrosion films, which could act as easy paths for H2O and CO2 to further react with Li+ and B3+. The X-ray photoelectron spectroscopy results and theoretical analysis show that LiBH4 tends to react with H2O and CO2 to form Li2B4O7, Li2CO3 and LiOH during the corrosion process. 相似文献
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Hui Zhang Liang Fang Mei-Bo Tang Hao-Hong Chen Xin-Xin Yang Xiangxin Guo Jing-Tai Zhao Yuri Grin 《Intermetallics》2010,18(1):193-198
High density polycrystalline CaCd2Sb2 and EuCd2Sb2 intermetallics are synthesized by Spark Plasma Sintering and their thermoelectric properties are investigated. X-ray diffraction measurements reveal both materials have a structure in space group, containing a small amount of CdSb as a second phase. Thermoelectric measurements indicate both are p-type conductive materials. The figure of merit value of CaCd2Sb2 is 0.04 at 600 K and that of EuCd2Sb2 is 0.60 at 617 K. Theoretical calculations show that CaCd2Sb2 is a degenerate semiconductor with a band gap of 0.63 eV, while EuCd2Sb2 is metallic with DOS of 13.02 electrons/eV. For deeper understanding of the better thermoelectric properties of EuCd2Sb2, its low temperature magnetic, transport and heat capacity properties are investigated. Its Nèel temperature is 7.22 K, convinced by heat capacity anomaly at 7.13 K. Hall effect convinced that it is a p-type conductive material. It has high Hall coefficient, high carrier concentration and high carrier mobility of +1.426 cm3/C, 4.38 × 1018/cm3 and 182.40 cm2/Vs, respectively. They are all in the magnitude of good thermoelectric materials. The Eu 4f level around Fermi energy and antiferromagnetic order may count for the better thermoelectric properties of EuCd2Sb2 than that of CaCd2Sb2. 相似文献
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A. V. Morozkin 《Journal of Alloys and Compounds》2003,360(1-2):L7-L8
Results of a powder X-ray diffraction investigation of new ternary compounds are reported. The compounds Y6CoBi2 [a=0.8312(1) nm, c=0.4144(1) nm], Ho6CoBi2 [a=0.8246(2) nm, c=0.4095(1) nm], and Tm6CoBi2 [a=0.8155(2) nm, c=0.4066(1) nm] crystallize in the hexagonal Zr6CoAs2-type structure (space group P6b2m No. 189). The Zr6CoAs2-type structure is a superstructure of the Fe2P-type structure. 相似文献
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We have investigated the magnetic properties and the 155Gd Mössbauer spectra of the ThCr2Si2-type compounds GdNi2Sb2, GdCu2Sb2 and GdAl2Ga2. These three compounds were found to order antiferromagnetically, with TN=6.5 K, 15.8 K, and 42.4 K respectively. The electric field gradient V22 derived from the quadrupole splitting of the Mössbauer spectra gives rise to a sign change at the end of the T3d series in GdT2Sb2, as was observed previously also for the corresponding compounds with Si and Ge. This behaviour was explained in terms of decreasing hybridization between the Gd valence electron states and the d electron states of the T atoms. 相似文献
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探究了使用大气等离子喷涂设备制备适合热喷涂使用的球形CaF2/BaF2共晶粉末的可能性。68%BaF2、32%CaF2粉末(质量分数)经过1 100℃真空烧结后,形成致密的块状氟化物共晶。机械破碎后的氟化物共晶经过等离子焰流重熔后得到了球形的氟化物共晶。使用F14-1流动性和松装密度测定仪测量球化前后粉末的流动性和松装密度。采用扫描电子显微镜,XRD表征球化前后粉末的形貌和物相组成。结果表明:球化后的粉末呈现较好的球形,球化后粉末的流动性和松装密度较球化前也有较大的改善:球化后共晶粉末的流动时间为55.20s/50g,松装密度为1.89g/cm3;另外,球化后共晶粉末还表现出良好的高温润滑性能:含有10%CaF2/BaF2共晶(质量分数)的镍基涂层在600℃和800℃的平均摩擦因数都小于0.3。 相似文献
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Mineaki Matsumoto Hiroshi Takayama Daisaku Yokoe Kazuo Mukai Hideaki Matsubara Yukio Kagiya Yuuji Sugita 《Scripta materialia》2006,54(12):2035-2039
The effects of La2O3 addition on thermal conductivity, phase stability and thermal cycle life of Y2O3 stabilized ZrO2 plasma sprayed coatings were investigated. Although low thermal conductivity as well as high resistance to sintering was achieved by La2O3 addition, it tended to also result in lower phase stability and thermal cycle life of the coatings. Optimization of the composition and structure of the coatings improved these properties, and the optimized coatings showed prolonged thermal cycle life. 相似文献
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Several binary stannides of the early transition metals T have been reported with the composition T2Sn3 previously. However, the present structure refinements from single-crystal X-ray data show that they have the compositions VSn2, NbSn2 and CrSn2 (R = 0.028, R = 0.018 and R = 0.021 with 17 variable parameters and 828, 512 and 440 structure factors respectively). Their orthorhombic Mg2Cu-type structure is closely related to the structures of MoSn2 (Mg2Ni type) and CuAl2. The latter structure type was confirmed for NbSnSb by a structure refinement from single-crystal data (R = 0.010 for eight variables and 254 F values). Electrical conductivity measurements show CrSn2 and MoSn2 to be metallic conductors. 相似文献