热处理温度对铝合金纳米TiO2复合涂层耐蚀性的影响

纳米TiO2耐蚀性能优良,采用溶胶-凝胶工艺、浸渍-提拉法在铝合金表面涂覆纳米TiO2复合涂层,并将涂层在不同温度下热处理,研究了热处理温度对纳米TiO2复合涂层耐蚀性能的影响.结果表明:100℃热处理的复合涂层的耐蚀性最佳,在3.5%NaCl溶液中腐蚀电流密度比铝合金基体降低了4个数量级,在基体表面形成了均匀的保护膜,对基体形成了良好的防护.     

脉冲电沉积Ni-P/纳米Al2O3复合镀层的性能

Ni-P/纳米Al2O3复合镀层具有良好的耐磨、耐腐蚀性能,但有关脉冲电沉积Ni-P/纳米Al2O3复合镀层的报道较少.采用脉冲电沉积方法制备了Ni-P/纳米Al2O3复合镀层,研究了复合镀层的表面形貌、结构及其在5%NaCl溶液中的耐腐蚀性能,并对300,400,500℃热处理后的复合镀层的显微硬度进行了测试.结果表明:Ni-P/纳米Al2O3复合镀层的耐蚀性优于1Cr18Ni9Ti不锈钢,但比Ni-P合金镀层差;随镀液中纳米Al2O3浓度增大,复合镀层的显微硬度提高,镀液中纳米Al2O3浓度为25.0 g/L时制得的复合镀层的硬度为685.5 HV;Ni-P/纳米Al2O3复合镀层经400℃热处理后硬度最高.     

Ni-纳米TiO2复合电镀层的制备与性能研究

用电镀的方法制备出Ni-纳米TiO2复合电镀层,讨论了表面活性剂、阴极电流密度、搅拌速率等对复合镀层硬度的影响并分析了纳米TiO2的加入对复合镀层硬度、耐蚀性的影响情况.结果表明,与纯镍镀层相比,Ni-纳米TiO2复合电镀层的硬度可提高90～190 HV;添加阳离子表面活性剂分散纳米TiO2所得复合镀层硬度最高,说明阳离子表面活性剂有利于纳米TiO2-Ni复合电沉积.浸泡试验表明,在硝酸溶液中复合镀层的腐蚀速率高于纯镍镀层的腐蚀速率,但远低于未镀覆钢板的腐蚀速率;极化曲线表明,与纯镍镀层相比,复合镀层的自腐蚀电位没有显著提高.说明在复合镀层中添加纳米TiO2不能改善其耐蚀性.     

Ni/SiC复合镀层腐蚀行为研究

研究了Ni/SiC复合镀层在3.5%NaCl溶液中的腐蚀行为.测定了Ni/SiC镀层在NaCl溶液中的失重曲线,利用solartron恒电位仪测定其极化曲线,借助扫描电镜对镀层表面形貌进行了观察.结果表明,随着腐蚀时间的延长,腐蚀失重逐渐增加,但腐蚀速率逐渐降低;Ni/SiC复合镀层与纯Ni镀层耐盐水腐蚀能力基本相当;Ni/SiC复合镀层在3.5%NaCl溶液中的开路电位要高于纯Ni镀层的开路电位;在3.5%NaCl H2O2溶液中,两种镀层的开路电位均明显正移,且Ni/SiC复合镀层自腐蚀电流降低,说明复合镀层耐盐水腐蚀能力有所提高.镀Ni层中引入SiC颗粒能使其组织细化,并促进复合镀层在3.5%NaCl溶液中发生钝化,可能是Ni/SiC镀层在盐水中耐蚀性能提高的主要原因.     

Ni-ZrO_2-CeO_2二元纳米复合镀层摩擦磨损及耐蚀性研究

利用超声-脉冲电沉积法在45钢基体上制备了纯Ni镀层、Ni-ZrO_2纳米复合镀层和Ni-ZrO_2-CeO_2纳米复合镀层,对比研究了3种镀层的表面形貌、显微硬度、摩擦磨损及耐蚀性能。结果表明与纯Ni镀层、Ni-ZrO_2纳米复合镀层相比,Ni-ZrO_2-CeO_2纳米复合镀层表面最光滑且晶粒最细小,表面显微硬度最高为494.18 Hv0.1;在施加载荷50N、转速300r/min、磨擦时间3min的磨损条件下磨损量最小为2.6mg且摩擦系数最小为0.285;在常温3.5%NaCl溶液腐蚀条件下腐蚀速率最低为0.060383mm/year,表面腐蚀特征不明显。镀层中共沉积的纳米ZrO_2、CeO_2颗粒充分发挥了二元纳米粒子协同生长的优势,使得镀层金属晶粒更加细化,表面更加平滑光整,镀层的耐腐蚀性能得到提高。     

Ni-SiC复合梯度镀层的耐腐蚀性能

Ni-SiC复合梯度镀层比普通复合镀层性能要优,应用要广,但过去对其耐蚀性研究不多.通过对电流密度、搅拌强度和镀液中Sic浓度等电镀工艺条件的优化,制备了新型Ni-SiC复合梯度镀层.采用扫描电镜对其表面和断面形貌进行了观察,并借助电化学手段研究了Ni-SiC复合镀层在3.5%Nacl腐蚀液和3.5%NaCl+0.3%H2O2腐蚀液中的耐蚀性能.结果表明:在复合镀层中,SiC微粒沿镀层生长的方向呈梯度分布,在镀层表面呈均匀弥散分布;在3.5%.NaCl腐蚀液中纯镍镀层的耐腐蚀能力与复合镀层相当;在3.5%NaCl+0.3%H2O2腐蚀液中,由于SiC微粒包裹在Ni-SiC复合镀层内,彻底改变了镀层的表面形貌和组织结构,细化了镀层晶粒,所以改善了Ni-SiC复合镀层的耐蚀性能.     

脉冲电沉积Ni-P/BN(h)复合镀层的组织结构与性能

目前,鲜见对Ni-P/Bn(h)复合电沉积层的制备及其性能的研究报道。在Q235钢表面脉冲电沉积了Ni-P/BN(h)复合镀层,并于400℃热处理80 min,对热处理镀层的组织结构、显微硬度、耐蚀性能和摩擦学性能进行了分析测试。结果表明:镀态复合镀层为非晶态结构,400℃热处理后发生晶化,显微硬度显著提高,达到907.5 HV2 N;在3.5%NaCl和10%H2SO4腐蚀介质中,镀层几乎未发生全面腐蚀;镀层在干摩擦条件下表现出良好的减摩耐磨性能,低载时为轻微磨粒磨损,随载荷增大表现为磨粒磨损和黏着磨损的混合磨损机制。     

电刷镀Ni-P／纳米WC复合镀层工艺及性能研究

为了改善电刷镀Ni-P镀层的硬度和耐磨性,通过在电刷镀Ni-P镀液中加入纳米WC微粒制备Ni-P/纳米WC复合镀层,研究了镀液中纳米WC含量与镀层中纳米WC含量的关系;测定了不同WC含量对镀层硬度和镀层结构的影响.考察了试样在1 mol/L H2SO4,1 moL/L HCl及3%NaCl介质中的耐蚀性.采用扫描电子显微镜(SEM)及X射线衍射(XRD)研究了Ni-P/纳米WC镀层的性能.结果表明,Ni-P/纳米WC电刷镀复合镀层耐蚀性能与原电刷镀Ni-P镀层相当,耐磨性优于电刷镀Ni-P镀层.镀液含25 g/L纳米WC时,电刷镀复合镀层的显微硬度为918 HV.     

热处理对Ni-P合金镀层组织结构、显微硬度与耐蚀性能的影响

目前,有关热处理对Ni-P合金镀层组织结构与性能的影响研究不够深入。采用脉冲电沉积方法在Q235钢表面制备Ni-P合金镀层,并在200～500℃下进行热处理。利用X射线衍射仪分析镀层的相结构,用电化学极化曲线和扫描电子显微镜(SEM)对镀层在3.5%NaCl,10%HCl和10%H2SO4溶液中的腐蚀行为进行了研究。结果表明,提高热处理温度,Ni3P相的析出速度增大,Ni-P合金镀层的晶化时间减少,达到最高硬度所需的热处理时间相应缩短,镀层经300℃和400℃热处理后的最高硬度分别达到862.8 HV2N和887.4HV2 N;Ni-P合金镀层热处理晶化后,其耐蚀性能显著降低,在3种腐蚀介质中均发生点蚀。     

Q235碳钢表面纳米TiO2复合膜的耐腐蚀性能

在低碳钢表面直接制备纳米TiO2薄膜,结合力不强,膜易脱落.为此,以Ni-P化学镀层作基体和膜之间的过渡层,然后采用溶胶凝胶-提拉法在Q235碳钢表面制备了均匀致密的纳米TiO2复合膜.研究了纳米TiO2复合膜的烧结温度、膜厚度对耐腐蚀性能的影响.结果表明:提拉3次,450℃烧结1 h的纳米TiO2复合膜在3%NaCl溶液中耐蚀性能较好;在紫外光照射下膜的腐蚀电位低于Q235碳钢基体,作为非牺牲性阳极对Q235碳钢具有优异的防腐蚀性能.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

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...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

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.     

Roman iron and steel: A review

ABSTRACT

The 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.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

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.……     

Deposition and Coating Properties on CVD Tungsten

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.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.