热浸镀铝时间对镀层生长的影响

利用溶剂法制备了热浸镀铝试样,借助扫描电镜观察了其微观形态,其镀层扩散层主要由Fe2Al5相构成。分析了750℃时不同浸镀时间下热浸镀扩散层的厚度,利用菲克第二定律对热浸镀扩散层的生长规律进行了理论分析,结合实验数据分析得知在浸镀时间延长时,镀层中Fe2Al5相会有横向生长,使得扩散层厚度与时间的平方根呈现速率下降的抛物线规律。     

304不锈钢热浸镀铝工艺及镀层的耐冲蚀性能

为提高304不锈钢在实际工况中应用时的耐腐蚀性能,采用熔剂法对304不锈钢热浸镀铝,并对镀铝层进行扩散退火处理,通过厚度测试,形貌观察及成分分析优选了热浸镀工艺及扩散退火工艺,并采用冲刷腐蚀试验研究了最佳工艺制备的镀层的冲蚀性能。结果表明:304不锈钢热浸镀Al-3.0%Si-0.5%RE,在740℃左右浸镀15min时,镀层厚度为100μm左右;在820℃扩渗4 h,获得了较好的扩渗层,其厚度约为115μm;冲蚀时间达到120 h时,经最佳条件热浸镀铝+扩散退火处理后镀层的冲蚀失重速率最小,为0.092 g/(h·m2),未热浸镀铝及扩散退火处理的304钢原始试样的冲蚀失重速度相对较快,其冲蚀腐蚀速率为0.121 g/(h·m^2),约为热浸镀铝试样的1.32倍。     

热浸温度对不同热浸镀层力学性能的影响

研究了不同热浸热浸温度对纯锌镀层和Zn-11%Al-3%Mg-0.2%Si-0.02%RE合金镀层中元素分布、镀层厚度的影响并对两种镀层中的物相进行了分析,同时研究了不同热浸温度对镀层试样抗弯曲强度和硬度的影响。结果表明两种镀层的厚度都随热浸镀温度的升高而减薄。随着热浸镀温度的升高,扩散阻碍层被迅速破坏,导致合金镀层中的Al含量出现了降低的现象。通过XRD结果分析得出,纯锌镀层内部主要包括Zn和FeZn8.75两种物质,合金镀层内部则主要包括Zn、Fe4Zn9、MgZn2、Al5Fe2。抗弯曲试验和硬度测试结果表明,两种试样的抗弯强度都随热浸温度的升高而降低。纯锌镀层试样的硬度随热浸温度的升高呈现降低趋势,而合金镀层试样的硬度则随热浸温度的升高呈上升趋势。     

铜热浸镀铝扩散层生长动力学模型

采用一浴法对铜进行了热浸镀铝试验,热浸镀时间为10~25s,热浸镀温度为963~1 013K。研究了热浸镀温度和时间对铜铝复合材料界面扩散层厚度的影响,采用XPL-15型偏光显微镜(PM)测量铜铝复合材料扩散层厚度,并依据热浸镀铝试验建立了铜铝复合材料界面扩散层生长动力学模型。结果表明,铜铝复合材料界面扩散层的生长动力学符合抛物线扩散规律,与热浸镀温度的指数成正比,与热浸镀时间成抛物线增长关系;铜热浸镀铝扩散层生长动力学模型的修正系数k与时间t存在线性关系。     

热浸镀镧铝钢的高温耐热行为研究

在20碳钢上分别制备了热浸镀纯铝和镧铝涂层.经过900℃×6h的扩散处理后,研究了涂层的抗氧化性能和组织形貌变化.结果表明:热浸镀镧铝试样表面的纯铝层厚度比热浸镀纯铝试样减少25%～35%;经扩散处理后,在800℃氧化的前40h,热浸镀纯铝试样氧化动力学曲线符合抛物线规律,40h后,氧化动力学曲线呈直线.在整个氧化期间.热浸镀镧铝试样的氧化动力学曲线都符合抛物线规律,且抗高温剥落性能同样优于热浸镀纯铝试样.组织形貌分析表明,镧抑制了扩散和高温氧化过程中扩散层/基体界面孔洞的形成和聚集,阻止了扩散层的内氧化.分析了镧对镀铝钢高温耐热行为的影响机理.     

钢基热浸镀锌铝合金的研究

为进一步提高镀锌层质量和耐腐蚀能力,通过在传统热浸镀锌中添加少量铝,获得了钢基热镀锌铝合金层。研究了钢基热浸镀锌铝合金镀过程中,助镀剂的组成,镀液温度、浸镀时间、钢基硅含量等因素对镀层厚度的影响,获得了一种耐腐蚀性好,结合力强和光滑的热镀锌铝合金层,该锌铝合金镀层与镀锌层相比,在二氧化硫气氛中的耐腐蚀能力有很大的提高。     

影响热浸镀铝层厚度的因素分析及预测模型的建立

BP神经网络预测模型可用于相关材料组织、性能与相关参数对应关系的预测,但目前还未见用于热浸镀铝层（表面层和金属间化合物层）厚度的预测。利用溶剂法对Q235钢热浸镀铝,以正交试验法分析了浸镀温度、时间、提升速度、浸镀液中硅含量4种因素对铝镀层厚度的影响,建立了相关的神经网络预测模型。结果表明：4种因素对铝表面层厚度影响的大小顺序为提升速度〉硅含量〉浸镀温度〉浸镀时间;对金属间化合物层厚度影响则为浸镀温度〉浸镀时间〉硅含量〉提升速度;利用正交试验数据对建立的BP神经网络预测模型进行训练后,对镀铝层厚度的预测结果与试验结果相符。     

热浸镀55%Al-Zn-1.6%Si合金钢板镀层表面形貌及组织特征研究

采用光学显微镜、SEM、EDS等实验手段,研究了Ti元素对热浸镀55 ％Al-Zn-1.6％Si板的镀层表面形貌、元素分布、成分组成、横截面相组成体积比的影响.结果表明:无添加Ti元素的1#镀铝锌产品表面锌花尺寸偏大且不均,Al、Zn、Si等元素在表面分布规律不明显,镀层总厚度在15～17 μm之间,其中外镀层15μm,内镀层1.8μm,镀层截面由约65％的富铝相+35％的富锌相组成;添加Ti元素的2#镀铝锌产品镀层表面光泽比1#亮丽,立体感效果显著,锌花尺寸也更加细碎均匀,Al、Zn、Si等元素呈现较明显的规律分布,镀层总厚度在24.3～26.7 μm之间,其中外镀层24.8μm,内镀层1.6 μm,镀层截面组织由约76.2％的富铝相+22.7％的富锌相及少量的富硅相组成.     

铝锌硅镀层的冲压性能

铝锌硅镀层(Galvalume)作为钢铁基体的热浸镀材料,具有良好的耐腐蚀能力,但是Galvalume镀层在受力变形时容易出现裂纹。针对热浸镀Galvalume镀层成形开裂问题,通过对不同镀层厚度(重量)镀铝锌板进行冲压试验和180°弯曲试验,观察裂纹源的产生。采用扫描电镜(SEM)和能谱(EDS)对镀层及中间过渡层进行研究,分析影响镀层冲压开裂的原因。结果显示:镀层的重量(厚度)是影响其冲压开裂的主要原因,随着镀层厚度的下降,镀层外侧受拉应力作用开裂趋势变小;开裂位置显示主要元素为Fe、Al、Si元素,变形过程中Galvalume合金过渡层相对于镀层更容易开裂;Galvalume合金过渡层的厚度是影响Galvalume冲压开裂的主要原因,随着合金过渡层厚度的降低,过渡层开裂趋势变小。     

添加稀土铈对热浸镀铝45钢的组织及其性能的影响

采用SEM和XRD研究了添加不同含量铈对45钢基热浸镀铝镀层及其退火后的组织和结构影响,并用氧化增重法考察了镀层的耐热性,用M-2000型摩擦磨损试验机测试了镀层退火后的耐磨性能。结果表明,镀液中稀土铈质量分数为0.1%~0.25%时,镀层晶粒细化、厚度降低,退火合金层厚度增加。稀土铈能抑制合金层的Fe2Al5相生长,使镀层合金层以FeAl3、少量Fe2Al5相为主,使退火合金层以FeAl、Fe3Al相为主。稀土铈含量为0.25%时,镀层的抗高温氧化性和镀层退火后在油润滑下的耐磨性最佳。     

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...     

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.……     

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.     

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.     

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.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

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.     

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