共查询到20条相似文献,搜索用时 112 毫秒
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腐蚀是影响镁及其合金大规模应用的关键技术难题之一,因可有效隔离金属基底与腐蚀介质的直接接触,从而降低腐蚀速率,制备超疏水表面成为提高镁合金耐蚀性的有效途径。通过一步电沉积方法,在AZ31镁合金基底上成功制备了铜-金属有机骨架-硬脂酸(Cu-MOF-SA)超疏水膜,并对超疏水膜的耐腐蚀性、化学稳定性和耐热性进行了综合研究。结果表明,表面的水接触角可达158°,超疏水膜覆盖的试样在3.5%NaCl溶液中表现出良好的耐腐蚀性能,相比AZ31镁合金基底,其腐蚀电位正移了0.24 V,腐蚀电流密度降低了1个数量级。在pH值为1~14的溶液中浸润24 h后,超疏水膜的水接触角仍可达135°以上,浸泡在pH=1的溶液24 h的超疏水膜的腐蚀电位比AZ31镁合金基底高0.21 V。在20~90℃空气中保温24 h后,超疏水膜的水接触角仍保持在154°以上,80℃下保温24 h后其腐蚀电位比AZ31镁合金基底的高0.22 V,腐蚀电流密度比AZ31镁合金基底的小1个数量级。结果表明,本研究制备的Cu-MOF-SA疏水膜具有良好的超疏水性和耐腐蚀性。 相似文献
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超疏水镁合金表面的防黏附和耐腐蚀性能 总被引:1,自引:0,他引:1
通过盐酸刻蚀、氨水浸泡和疏水长链接枝,成功构建得到接触角达154°、滚动角为6°的超疏水镁合金表面。利用接触角测试、扫描电镜观察、红外光谱分析、防黏附和电化学实验等分别对超疏水镁合金表面的润湿性能、表面微结构与化学组成、防黏附行为以及耐腐蚀性能进行了考察。结果表明:盐酸刻蚀和氨水浸泡使得镁合金表面产生了微-纳复合结构,而硬脂酸修饰使疏水烃基长链通过化学键接枝到具有微-纳复合结构的镁合金表面。正是由于其特殊的表面微结构和化学组成,使得超疏水镁合金表现出良好的防黏附和耐腐蚀性能。 相似文献
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AZ91D镁合金表面熔盐置换扩散涂层组织及耐腐蚀性能研究 总被引:1,自引:0,他引:1
采用AlCl3-NaCl熔盐自发置换扩散工艺在AZ91D镁合金表面制备镁铝金属间化合物涂层,并利用开路电位、电化学阻抗方法对镁合金及熔盐置换扩散改性处理试样在3.5%(质量分数)NaCl溶液中的腐蚀行为进行比较研究。结果表明:熔盐自发置换扩散铝涂层在温度为400℃,保温8h的工艺条件下呈现出了明显的分层结构特征。根据组织结构不同,可将其分为:颗粒状形貌的外层和具有网状结构的内层;经表面熔盐自发置换扩散处理后的镁合金试样,腐蚀电位比未改性的AZ91D镁合金大幅提高,膜层阻抗约为未改性的AZ91D镁合金的10倍。 相似文献
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AZ91D镁合金表面钙系磷酸盐膜层的制备及其耐蚀性 总被引:1,自引:0,他引:1
为了降低AZ91D镁合金活泼的化学性质,使其成为耐蚀性更好的医用金属材料,在不同pH值及反应温度等条件下对AZ91D镁合金进行钝化,观察了不同条件下制备的膜层的表面形貌、元素构成,并测试了其电化学性质,研究了磷化的pH值和温度对磷化膜性能的影响。结果表明:磷化液的温度及pH值对磷化膜性能有重要影响,当pH值为2.8,温度为40℃时,制备的磷化膜为针状鳞片、尺寸均一,膜层覆盖最为致密细腻,表面膜层中主要生成了CaHPO_4·2H_2O化合物,即DCPD,还有少量Ca_3(PO_4)_2,膜层在AZ91D表面形成了稳定的钝化层,有效降低了其化学活泼性,大幅提高了其耐蚀性。 相似文献
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通过微弧氧化技术在MB8镁合金表面形成微细表面结构,再利用自组装方法在微弧氧化层表面制备1H,1H,2H,2H-全氟葵烷基三氯硅烷(FDTS)自组装分子膜。采用扫描电镜、表面粗糙度仪、X射线衍射仪、表面硬度仪、接触角测量仪和UMT-2型摩擦磨损试验机评价膜层形貌结构、力学特性、润湿性及其微摩擦学特性。结果显示,镁合金表面经微弧氧化处理和自组装分子膜修饰后,表面润湿性经历了由亲水到超亲水再到超疏水的转变过程。超疏水表面的获得是由微弧氧化处理得到的表面粗糙结构和低表面能物质自组装分子膜共同作用的结果。对试样进行摩擦磨损测试的结果显示,致密层和疏松层以及经自组装分子膜修饰后的膜层均具有比镁合金基底更好的抗磨性能;基于自组装技术制备的疏水、超疏水表面形成的边界润滑膜在一定载荷条件下均能有效地减少基底的摩擦系数,边界润滑膜失效后,基底表面特性占主导地位。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di... 相似文献
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A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils. 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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S. K. Malhotra Paramanand Singh A. Thirunavukkarasu 《Materials and Manufacturing Processes》2006,21(7):652-657
Al2O3-ZrO2 nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness. 相似文献
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The end of over unit products of more than Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits beer wine yellow wine fruit syrup wine others cover over % of the national top-branded liquor products.…… 《中国标准化(英文版)》2008,25(1):30
The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.…… 相似文献
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Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster. 相似文献