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TiO_2薄膜对金刚石磨料的抗氧化性能及磨削性能的影响 总被引:1,自引:1,他引:0
为解决传统电镀工艺在进行金刚石磨料表面改性时所产生的能耗及环境污染问题,采用溶胶-凝胶工艺在金刚石表面涂覆了一层致密的TiO2薄膜.通过扫描电镜、能谱、红外光谱、Raman光谱和综合热分析等手段对涂膜后的金刚石磨料表面形貌、结构和性能进行表征.结果显示:表面涂覆TiO2薄膜的金刚石磨料在空气中开始氧化并发牛质量损失的温度为700℃,较未涂膜的金刚石磨料的起始氧化温度提高150℃.用涂TiO2膜金刚石磨料制备的陶瓷结合剂金刚石砂轮,其硬度较未涂膜磨料制备的砂轮提高13%,对硬质合金的摩耗比提高2.2倍. 相似文献
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热喷涂镍-铬基涂层的高温氧化性能 总被引:1,自引:0,他引:1
为了提高钢体结构材料的高温氧化性能,采用超音速电弧喷涂技术和微弧等离子喷涂技术,在45钢基体上分别制备了Ni-Cr基涂层和Ni-Cr/ZrO2复合梯度涂层,对45钢基体、Ni-Cr基涂层和Ni-Cr/ZrO2复合梯度涂层进行了1100℃高温氧化实验,采用热重分析(TGA)、X射线衍射(XRD)、扫描电镜(SEM)等方法研究了涂层的氧化性能.结果表明,Ni-Cr基涂层和Ni-Cr/ZrO2复合梯度涂层高温氧化后,表面组织结构致密,与45钢基体相比,具有更优良的抗高温氧化性能. 相似文献
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采用溶胶-凝胶(sol-gel)法在中间相沥青基碳纤维的表面制备了碳化钽(TaC)涂层。运用FTIR对钽溶胶、凝胶的特征基团进行了分析,借助X射线衍射、扫描电镜分析TaC涂层纤维的物相组成和微观结构,并利用热失重研究了涂层对碳纤维抗氧化性能的影响。研究结果表明,经过二次涂层,1600℃热处理后,碳纤维表面的TaC涂层均匀致密,无明显孔洞,呈连续的层状结构,涂层厚度约为150nm,且涂层中存在大面积的白色TaC颗粒。研究结果还表明,二次涂层后碳纤维起始氧化温度比无涂层碳纤维提高了250℃,且纤维在800℃以下几乎没有明显的失重,氧化终止温度也提高到870℃,该涂层提高了碳纤维的抗氧化性能。 相似文献
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采用准原子层沉积(Quasi Atomic Layer Deposition-QALD)技术在纳米金刚石表面沉积硅镀层。通过硅烷气体在纳米金刚石颗粒表面饱和吸附,然后原位热解的分步反应实现了硅镀层对纳米金刚石的完整包覆。实验使用TEM、XRD、FTIR和TGA-DSC等分析方法研究了镀硅纳米金刚石的形貌、结构、表面吸附状态和热稳定性。结果表明,SiH4气体循环吸附-热解的QALD方法可在纳米金刚石颗粒表面形成均匀连续、厚度可控的硅镀层。热解反应温度为600℃时,硅镀层为立方相。纳米金刚石镀硅后,热稳定性显著提高,温度升高到1000℃也没有明显的氧化反应发生。 相似文献
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采用Ti、Al和超硬材料颗粒(金刚石/cBN)为原料,通过熔盐处理法在超硬材料表面反应形成了钛铝化合物涂层,利用XRD、SEM和EDS对涂层的化学组成、相组成和微观结构进行了分析和表征。结果表明:原料经过熔盐处理,反应形成了Al_3Ti,同时,在超硬材料表面主要形成的是连续的、致密的Ti涂层。然后在Ti涂层上形成少量的Al_3Ti颗粒组织。在金刚石表面上形成的Al_3Ti颗粒组织平均粒度约为0.4μm,在cBN表面上Al_3Ti颗粒组织粒度约为0.5~4μm。 相似文献
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采用溶胶-凝胶工艺在经过微弧氧化预处理的钛基体表面制备二氧化钛(TiO2)-含氟羟基磷灰石(FHA)-羟基磷灰石(HA)梯度结构的生物陶瓷涂层.采用X射线衍射检测了涂层的相组成,采用扫描显微镜观察了梯度涂层的形貌,采用划痕法测定了涂基结合力,结果表明:所制备的涂层是均匀和致密的具有梯度结构的TiO2-FHA-HA涂层;与单一的HA涂层相比梯度的引入显著提高了涂基结合力.生物溶解性实验结果显示了溶解速度FHA小于HA,这就表明了可以通过梯度设计来提高涂层的植入寿命. 相似文献
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通过钕-铝系列色料合成实验,分析不同配比及不同矿化剂等对色料呈色效果的影响,确定最佳工艺方法。对实验结果进行XRD及色度分析,确定其主晶相为钕酸铝,试样的明度均在70以上,色彩鲜艳亮丽。 相似文献
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F. -T. Liou C. Y. Yang K. Hakim S. N. Levine 《Journal of Applied Electrochemistry》1983,13(3):377-382
Single crystal In2O3 shows promise as a photoanode for the decomposition of water. Because of various difficulties in the preparation of the single crystal material, two simple techniques were developed for the preparation of polycrystalline In2O3 anodes. One method involves the thermal decomposition of the nitrate while the other utilizes the chemical vapour deposition technique. Voltammograms and photoresponse spectra of these anodes are compared to the single crystal material. Among other observations, it is noted that the quantum efficiencies of the thermally decomposed films are comparable to the single crystal material. It is also shown that the on-set potential can be shifted to more negative values by forming the mixed oxide In2O3/Y2O3. 相似文献
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《Journal of the European Ceramic Society》2022,42(13):5820-5830
Cerium oxide doped with oxides of rare earth elements is a multifunctional material, a wide range of uses which is associated with its unique physicochemical properties. Phase diagrams of multicomponent systems are the physicochemical basis for the creation of new materials with improved characteristics.In this work, phase equilibria in ternary CeO2–La2O3–Dy2O3 and binary La2O3–Dy2O3 systems in the whole concentration range were studied. No new phases have been identified in these systems. An isothermal section of the phase diagram of the CeO2–La2O3–Dy2O3 system at a temperature of 1500 °С is constructed. No new phases have been detected in the system. It was found that in the studied ternary system solid solutions are formed on the basis of (F) modification of CeO2 with structure of fluorite type, monoclinic (B), cubic (C) and hexagonal (A) modifications of Ln2O3.In the La2O3–Dy2O3 binary system (1500–1100 °С) three types of solid solutions are formed: based on hexagonal modification A-La2O3, monoclinic modification B-Dy2O3 and cubic modification C-Dy2O3 separated by two-phase fields (A+B) and (B+C), respectively. The boundaries of the regions of homogeneity of solid solutions based on A-La2O3 are determined by compositions containing 35–40, 20–25, 15–20 mol% Dy2O3 at 1500, 1250, 1100 °C, respectively. From the obtained data it follows that the solubility of Dy2O3 in the hexagonal modification of lanthanum oxide is 39 mol% at 1500 °C, 23 mol. % at 1250 °C and 16 mol% at 1100 °C. The limits of existence of solid solutions based on monoclinic B-modification are determined by compositions containing 30–35, 65–60 (1250 °С), 35–40, 55–60 (1100 °С) 40–45, 70–75 (1500 °C) mol% Dy2O3.In the studied system, with a decrease in temperature from 1500° to 1100°C, there is a decrease in the solubility of La2O3 in the crystal lattice of cubic solid solutions of C-type from 16 to 10 mol%. 相似文献
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以Al2O3, Fe2O3和Na2CO3为原料,对Na2O-Al2O3-Fe2O3系烧结过程中的反应行为进行了详细研究. 基于溶出率与时间、温度的关系,证明Na2O×Al2O3和Na2O×Fe2O3的生成反应动力学都服从Zhuralev-Lesokin-Tempelman模型,表观活化能分别为186.59和80.92 kJ/mol,表明Na2O×Fe2O3比Na2O×Al2O3在动力学上更易形成;Al2O3易与Na2O×Fe2O3反应形成Na2O×Al2O3和Fe2O3,在1273 K烧结30 min,所得熟料Al2O3溶出率达98.51%;Fe2O3对Na2O×Al2O3的形成有双重作用,在1273 K下可加速Na2O×Al2O3的形成,超过1323 K,促使Na2O×Al2O3分解成Na2O和b-Al2O3,且随着温度升高或时间延长,分解程度增高,从而导致熟料中Al2O3溶出率显著降低. 相似文献
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Separation of phases was investigated in the hexagonal (rhombohedral) systems Al2O3−Cr2O3 and Al2O3−Cr2O3−Fe2O3. The binary system shows a miscibility gap with a Tc of 950°C; the miscibility gap for the ternary system was determined for a constant Cr2O3 content of 16.6 mol%. Dark field transmission electron microscopy of solid solutions annealed within the miscibility gap showed dark and light lamellas ∼50 to 200 Å thick. X-ray diffraction results for the solid solutions in the ternary system indicated that, in the early stages of annealing, broadening occurred only on (hkl) reflections where l≠0. There was no major change in the X-ray diffraction patterns of the annealed solid solutions in the binary system. Electron diffraction results indicated, however, that phase separation in both systems proceeded in the [001] direction. Solid solutions in the binary system separated very slowly; the separation could be enhanced hydrothermally. The mechanism of the separation of phases in both systems is spinodal and proceeds as follows: solid solution→intermediate modulated phase→equilibrium phases. 相似文献
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-Al2O3 formation fromm-Al2O3 was found by a new convenient technique. By thermal decomposition of a complex compound, trioxalatoaluminate Na
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[Al(C2O4)3]yH2O(0.091 x 0.333;y= 3), a very fine powder ofm-Al2O3 was formed. The decomposition process was examined by thermal analysis and X-ray diffraction and the phase relation of the system Na2O-Al2O3 in the midtemperature region between 600 and 1200° C is discussed briefly. The tablet ofm-Al2O3 was fired at 1600° C for 30 min to prepare dense-Al2O3 ceramics, the apparent density of which was greater than 95% of the theoretical value. The sintered tablet was examined from the structural point of view and the electrical conductivity was measured by an a.c. method to verify that the procedure of the complex decomposition is a suitable technique for-Al2O3 synthesis. 相似文献
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《Journal of the European Ceramic Society》2000,20(5):625-630
Ceramic compacts in the systems Al2O3–Y2O3, Cr2O3–Y2O3 and Y3(CryAl1-y)5O12 (Cr-doped YAG) were prepared by solid state reaction in calcined co-precipitated powder mixtures of appropriate compositions. Various solid-solution phases were formed, e.g. Y3(Al1-xCrx)5O12, YAlyCr1-yO3 and Al2-xCrxO3. Composite materials in the pseudo-binary or ternary systems Al2O3–Y3Al5O12, Cr2O3–Y2O3 and Y3(Al1–xCrx)5O12–YAlyCr1–yO3–(AlzCr1−z)2O3 were obtained by hot-pressing appropriate powder precursors at 1600–1650°C for 1 h. The microstructure of the prepared materials was studied in a scanning electron microscope with element analysis facilities. X-ray diffraction was used to reveal the phases present and their lattice parameters. The chemical compatibility of these phases was investigated. The results are discussed with a special emphasis on the solubility of Cr in the YAG structure, and on the compatibility relationship between Cr-doped YAG and its neighbouring phases. A gel-coating process for preparing Al2O3–YAG composites with tailored microstructures is also described. 相似文献
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The purpose of this research is to evaluate the bactericidal capacity of different Advanced Oxidation Treatments (AOTs) based on ozone: ozone, ozone/hydrogen peroxide and ozone/titanium dioxide on a wild strain of Clostridium perfringens, a fecal bacterial indicator in drinking water. The dose of ozone consumed ranges from 0.6 mg L?1 min?1 to 5.13 mg L?1 min?1 depending on the process and on the sample. In the treatments combined with O3, H2O2 dose utilized is 0.04 mM and TiO2 dose, 1 g L?1. In order to evaluate the influence of natural organic matter and suspension solids over the disinfection rate, treatments are performed with two types of water – natural water from Ebro River (Zaragoza, Spain) and NaCl solution 0.9%. To achieve 4 log units of inactivation, 3.6 mg O3 L?1 is necessary in O3 treatment, 4.25 mg O3 L?1 in O3/TiO2 system and 2.7 mg O3 L?1 in O3/H2O2 after processing the natural water. In NaCl solution, to get the same inactivation, 0.42 mg O3 L?1 is necessary in O3 treatment, 1.15 mg O3 L?1 in O3/TiO2 system and 0.06 mg O3 L?1 in O3/H2O2 process. Even though the three treatments studied have a high bactericidal activity due to the number of surviving bacteria decreases to non-detectable levels, O3/H2O2 is the most effective system for eliminating C. perfringens cells in a lower contact time, followed by O3 and finally O3/TiO2 system. 相似文献