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WC-Co,NiCr-Cr3C2喷涂层耐冲蚀、耐磨性优良,但耐盐酸腐蚀报道较少.为此,采用超音速火焰喷涂(HVOF)工艺制备了WC-Co和Cr3C2-NiCr涂层,测定了涂层的孔隙率和结合强度,用XRD分析了涂层腐蚀前后的相结构及在1 mol/L HCl溶液中浸泡涂层材料的失重情况,分析了涂层的均匀腐蚀机理.结果表明:WC-Co和Cr3C2-NiCr涂层组织较为致密,孔隙率分别为2.67%,4.39%,结合强度分别为49.576,41.023 MPa.Cr3Cr2-NiCr涂层中相结构复杂,涂层中Cr3C2少量分解且含有非晶相;经1 mol/L HCl溶液浸泡后WC-Co涂层和Cr3C2-NiCr涂层失重较少.涂层的腐蚀机理为选择性腐蚀.缺陷越少涂层的耐蚀性越好,减少涂层中的孔隙、显微裂纹和夹杂等缺陷是提高涂层耐蚀性的关键. 相似文献
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超音速等离子与HVOF喷涂WC-Co涂层的冲蚀磨损性能研究 总被引:12,自引:1,他引:11
用超音速等离子喷涂(HEPJet)和两种进口高速氧燃气火焰喷涂(HVOF)设备(JP-5000 和DJ-2700)制备WC-Co涂层,进行了孔隙率、显微硬度、结合强度及30°和90°攻角的冲蚀磨损对比实验,分析了涂层的SEM磨损形貌.结果表明,超音速等离子喷涂WC-Co涂层综合性能与JP-5000喷涂WC-Co涂层相当,优于DJ-2700;在30°冲蚀磨损条件下,WC-Co涂层的失效行为表现为疲劳剥落和微切削两种特征;在90°冲蚀磨损时,涂层的失效主要是垂直表面的磨粒冲击力导致涂层疲劳剥落. 相似文献
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Cr对超音速火焰喷涂WC-Co涂层抗中性盐雾腐蚀性能的影响 总被引:1,自引:0,他引:1
研究了超音速火焰喷涂(HVAF)WC-Co和WC-CoCr涂层的抗化学腐蚀性能。采用XPS对超音速火焰喷涂涂层的表面和内部进行了分析,在中性NaCl溶液中对涂层进行了电化学分析。结果表明,WC-Co中的粘结相Co主要呈金属单质,而WC-CoCr涂层中粘结相分别呈单质Co和Cr2O3。电化学极化测试表明,WC-Co涂层处理明显提高了基体的腐蚀电位,而添加Cr后则进一步提高了腐蚀电位。400 h中性盐雾腐蚀结果表明,WC-CoCr涂层的抗化学腐蚀性能优于WC-Co涂层的。腐蚀后的SEM表明,腐蚀介质先腐蚀涂层中的粘结相,当腐蚀介质扩散到基体中则优先腐蚀基体。添加少量的Cr在粘结相中形成了Cr2O3陶瓷钝化相,有利提高HVAF WC-Co涂层的抗腐蚀性能。 相似文献
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为了改善工件表面的抛光效果,解决传统机械抛光对抛光工件几何形状的限制,提高实际工程中对工件的抛光效率,本文介绍了一种全新的抛光工艺——电解抛光。电解抛光工艺与工件的材质、电流大小以及电解液的温度等参数密切相关,合理的控制这些工艺参数才能达到理想的抛光效果。本文主要探究电流密度、抛光温度以及阴阳极间的距离等因素对抛光效果的影响。 相似文献
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Ni对TiC-Ni超音速火焰喷涂层组织和耐磨性的影响 总被引:2,自引:1,他引:1
Ni对Ti-Ni-C体系SHS反应中的热力学与动力学均有重要影响,Ni在超音速火焰喷涂合成中的作用尚不明确.利用超音速火焰喷涂合成技术制备了3种不同Ni含量的TiC-Ni金属陶瓷涂层,并对涂层进行了组织和性能研究.结果表明,Ni在喷涂过程中起到了吸收反应热、减缓喷涂合成过程中粉末组分的氧化、并在涂层中黏结相金属的作用.原料中的Ni含量对涂层的组织和性能影响较大,Ni含量低涂层中含有大量氧化物,且组织疏松、滑动磨损性能差;随着Ni含量升高到40%时,涂层的氧化物含量降低,滑动磨损性能增强; Ni含量过高,涂层中Ni片层增多,硬质相间距加大,涂层的耐磨损性能有所降低. 相似文献
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超音速火焰喷涂WC-Co与NiCr-Cr2C3涂层磨损性能研究 总被引:3,自引:0,他引:3
采用超音速火焰喷涂(HVOF)工艺制备了WC-Co和NiCr-Cr2C3涂层,测定了涂层孔隙率、显微硬度及油润滑下摩擦磨损过程中涂层材料失重,得出涂层摩擦系数随时间的变化关系,分析了涂层摩擦磨损机理.结果表明,WC-Co和NiCr-Cr2C3涂层致密,孔隙率分别为1.29%和1.08%,显微硬度分别为1140HV0.3和950HV0.3.两种涂层均在摩擦时间25min时进入稳定磨损阶段,稳定摩擦系数均为0.1,涂层摩擦失重极小.油润滑下WC-Co涂层的摩擦磨损方式主要以为接触疲劳为主,伴随轻微的粘着磨损和磨粒磨损;NiCr-Cr2C3涂层碳化物的剥落和表面划痕较为明显,表面裂纹明显增多. 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