钛合金表面等离子喷涂制备ZrO2—Ti系功能梯度涂层

研究了等离子喷涂法制备ＺｒＯ２－Ｔｉ系功能梯度涂层。结果表明，采用等离子喷涂工艺制备功能梯度涂层是可行的，涂层与基体除以机械咬合方式结合外，还存在着少量冶金化学化学反应结合，添加Ｎｉ／Ａｌ和ＳｉＯ２有助于提高涂层的结合强度。     

钛合金表面等离子喷涂制备ZrO2─Ti系功能梯度涂层

研究了等离子喷涂法制备ＺｒＯ２Ｔｉ系功能梯度涂层。结果表明，采用等离子喷涂工艺制备功能梯度涂层是可行的，涂层与基体除以机械咬合方式结合外，还存在着少量冶金化学反应结合，添加Ｎｉ／Ａｌ和ＳｉＯ２有助于提高涂层的结合强度     

Al_2O_3/20%Ni网状复合材料抗热震性研究

采用热压方法制备了Ａｌ２Ｏ３／２０％Ｎｉ网状复合材料,通过压痕－淬火法在３００－９００℃淬火温差范围内评估了热震抗力．结果表明,复合材料的抗热震性明显高于单相Ａ１２Ｏ３陶瓷．根据材料的力学和物理性能,计算了Ａ１２Ｏ３陶瓷和Ａｌ２Ｏ３／２０％Ｎｉ网状复合材料的抗热震因子Ｒ＇和 Ｒ＂＂,结果表明,复合材料的抗热震因子亦大于单相Ａｌ２Ｏ３陶瓷,与热震实验结果相吻合．     

SiO2添加剂对8%Y2O3稳定的ZrO2涂层热震前后表面形貌的影响

在8％Y2O3稳定的ZrO2陶瓷涂层中添加SiO2，使陶瓷涂层的抗热震性能得到提高，这主要是SiO2的加入使涂层抗热震前后的表面形貌发生了很大的变化。由于ZrO2与SiO2热膨胀系数不同，使涂层利于产生细微的网状裂纹，增加了微裂纹密度和孔隙，从而降低了涂层的弹性模量，释放了涂层中的应力，使涂层的抗热震失效能力得到提高。其中，SiO2加入量为3％(质量分数)效果最佳，过量的加入，会使孔洞加大，促进裂纹的扩展、断裂，不利于提高涂层的抗热震性能。     

CeO2添加剂对等离子喷涂ZrO2涂层抗热震性的影响

采用SEM,EPMA和热震方法,研究了CeO2添加剂对等离子喷涂ZrO2i涂层抗热震性能的影响。结果表明：当CeO2由0增加到9.0%（质量分数,下同）时,涂层的抗热震起裂次数和失效次数分别由32次和46次增加到76次和105次;继续增加CeO2,涂层的抗热震性能急剧下降。ZrO2 9.0?O2涂层在热循环中形成的网状微裂纹,不仅可降低涂层中的应力,也可提高涂层开裂的临界温差,从而可改善其抗热震性能。     

TiAlCr涂层对TiAl金属间化合物抗熔融硫酸盐热腐蚀的影响

研究了溅射ＴｉＡｌＣｒ 涂层对ＴｉＡｌ 金属间化合物抗硫酸盐热腐蚀性能的影响。结果表明,８５０ ℃时,９０ ％ Ｎａ２ＳＯ４ ＋ １０ ％ Ｋ２ＳＯ４ 中Ｔｉ５０Ａｌ 和Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ 都遭受严重热腐蚀。ＴｉＡｌＣｒ 涂层能大大改善ＴｉＡｌ 金属间化合物的抗热腐蚀性能。带Ｔｉ５０Ａｌ１０Ｃｒ 涂层的Ｔｉ５０Ａｌ 表面形成一层完整致密的Ａｌ２Ｏ３ 膜, 涂层与基材之间无明显互扩散。带Ｔｉ５０Ａｌ１０Ｃｒ 涂层的Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ 表面虽然也形成Ａｌ２Ｏ３ 膜, 但在其上面长出一些ＴｉＯ２ 瘤。这可能是涂层与基材之间的互扩散导致涂层中Ｔｉ 含量增加,Ａｌ 含量减少而生成ＴｉＯ２ 的结果。将涂层成分调整为Ｔｉ５０Ａｌ２０Ｃｒ 后, 带Ｔｉ５０Ａｌ２０Ｃｒ 涂层的Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ 表面生成了连续的Ａｌ２Ｏ３ 膜, 其抗热腐蚀性能良好。     

等离子喷涂Al2O3与Cr2O3涂层性能的研究

对等离子喷涂Ａｌ２Ｏ３、Ｃｒ２Ｏ３涂层耐蚀性和耐磨性的试验研究表明,在３．５％ＮａＣｌ介质中,Ａｌ２Ｏ３涂层耐蚀性优于Ｃｒ２Ｏ３涂层;在滑动磨损条件下,Ｃｒ２Ｏ３涂层的耐磨性优于Ａｌ２Ｏ３涂层。     

铸铁坩锅抗铝融蚀等离子喷涂技术

针对提高化铝用铸铁坩埚抗融蚀寿命的实际问题,选用价格较低、耐高温、抗融蚀性好的Ａｌ２Ｏ３陶瓷材料作为坩埚内壁的工作层,采用等离子喷涂技术来提高其抗融蚀性。但由于Ａｌ２Ｏ３陶瓷涂层的致密性差、结合强度及抗热震寿命低等缺点,不适宜化铝坩埚在７２０℃长时间加温,且液铝呈搅拌行为的工作条件下使用。本文在Ａｌ２Ｏ３喷涂粉末中加入１３％ＴｉＯ２,促使涂层的组织结构发生变化,提高了涂层的结合强度,改善了涂层的致     

纳米SiCw晶须/ZrO2复合热障涂层的制备与性能

运用微弧等离子喷涂制备了碳化硅晶须(SiCw)掺杂部分稳定ZrO2(YPSZ)复合热障涂层(CTBCs),对涂层进行了显微组织观察、EDS分析、XRD分析和抗热震性能试验.喷涂过程中,复合粉末里的部分SiCw在高温下分解产生的气体夹杂在熔融的颗粒内形成气孔,另一部分沉积在涂层中起到降低热应力和钉扎、桥联作用.结果表明,随着粉末中SiCw含量的增加,复合陶瓷层的孔隙率呈增大趋势;复合涂层的抗热震性能优于单纯氧化锆涂层,SiCw含量为20%的复合涂层的抗热震性能最优.     

等离子喷涂纳米Al2O3/TiO2陶瓷复合涂层高温氧化和热震性能研究

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。     

Crystal structures and structural relationships of KFe2(SeO2OH)(SeO3)3 and SrCo2(SeO2OH)2(SeO3)2

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 ų, 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 ų , 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 ).     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

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.     

Corrosion characteristics of LiBH4 film exposed to a CO2/H2O/O2/N2 mixture

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.     

Synthesis and properties of CaCd2Sb2 and EuCd2Sb2

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.     

MoS2 coated with Al2O3 for Ni-MoS2/Al2O3 composite coatings by pulse electrodeposition

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.     

New Zr6CoAs2-type compounds: Y6CoBi2, Ho6CoBi2 and Tm6CoBi2

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.     

Gd Mössbauer effect and magnetic properties of GdNi2Sb2, GdCu2Sb2 and GdAl2Ga2

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 T_N=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.     

等离子球化制备球形CaF2/BaF2共晶粉末*

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。     

Thermal cycle behavior of plasma sprayed La2O3, Y2O3 stabilized ZrO2 coatings

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.     

Investigation of reaction between LiNH2 and H2

The reactions for LiNH₂ under a H₂ and an Ar flow were investigated, respectively. The results showed that LiNH₂ can be converted into LiH and NH₃ by reacting with H₂ under a H₂ flow condition, whereas LiNH₂ is converted into Li₂NH and NH₃ by decomposition under an Ar flow. Moreover, the reaction between LiNH₂ and H₂ can be accelerated by mixing LiNH₂ with LiH as well as doping LiNH₂ with TiCl₃. The confirmation of reaction between LiNH₂ and H₂ is helpful for the deeper insight in the systems of Li–N–H and Li–Mg–N–H for hydrogen storage materials.