SiC/DLC过渡层对类金刚石薄膜力学性能的影响

采用等离子体浸没离子注入及沉积技术在钛合金(Ti6Al4V)表面制备了类金刚石薄膜和含有SiC/DLC过渡层的类金刚石薄膜。采用拉曼光谱及扫描电子显微镜分析了薄膜的成分和结构,并利用超显微硬度计、薄膜结合力测试仪和往复式摩擦实验机研究了薄膜的硬度、韧性、膜/基结合力和耐磨性。研究结果表明,SiC/DLC过渡层可以提高钛合金(Ti6Al4V)表面类金刚石薄膜的韧性及膜/基结合力,与未制备过渡层的类金刚石薄膜相比,含有SiC/DLC过渡层的类金刚石薄膜的耐磨性明显提高。     

脉冲真空弧源沉积类金刚石薄膜耐磨特性研究

本文利用脉冲真空弧源沉积技术在Cr17Ni14Cu4不锈钢和Si(100)基体上制备了类金刚石(DLC)薄膜,研究在不同基体偏压下,DLC薄膜的结构与性能.采用拉曼光谱和X射线光电子能谱(XPS)研究DLC薄膜的原子结合状态,利用CSEM销盘摩擦磨损试验机研究其耐磨性,利用HXD1000B显微硬度仪测试其显微硬度,并采用压痕法评价其结合力.研究结果表明:DLC薄膜与基体结合牢固.随着基体偏压的提高,DLC薄膜内sp3键含量增大,薄膜硬度提高.Cr17Ni14Cu4不锈钢表面沉积DLC薄膜后,耐磨性大幅度提高,本文探讨了DLC薄膜的耐磨机理.     

不锈钢表面沉积DLC膜的结构和性能

应用线性离子束复合磁控溅射技术在不锈钢和硅片基体上制备DLC膜,研究了基体偏压和过渡层的厚度和结构对DLC薄膜结构和性能的影响。结果表明,在过渡层相同偏压为-200 V的条件下,薄膜中的sp3键含量更低,但是薄膜结构致密性的提高使其硬度和膜基结合力反而提高;在偏压为-200V的条件下,随着过渡层厚度及层数的增加DLC薄膜中sp3含量均降低,同时过渡层和多层薄膜的硬度减小;在偏压为-100V条件下,过渡层厚度和层数对DLC薄膜sp3的含量没有明显的影响。当过渡层厚度为1.7μm、结构为Cr/CrC时,在11Cr17不锈钢基体上可制备出厚度为4.92μm、硬度为29.4 GPa、摩擦系数小于0.1、结合力高于70 N综合性能最佳的DLC薄膜。     

类金刚石薄膜在不锈钢表面结合强度及耐腐蚀性研究

类金刚石(DLC)薄膜与不锈钢的结合强度是DLC薄膜应用于血管支架表面改性的关键技术问题.利用磁过滤阴极真空弧源沉积方法在316L不锈钢表面沉积DLC薄膜,研究沉积时基体偏压、薄膜厚度以及钛过渡层对DLC薄膜与基体结合强度的影响.研究结果表明,316L表面制备相同厚度的DLC薄膜,采用-1000V脉冲偏压制备的薄膜结合强度明显优于-80V直流偏压下制备的DLC薄膜;随着DLC薄膜厚度的增大,DLC薄膜与316L基体的结合力下降;316L不锈钢表面制备一层100nm的钛过渡层之后可以改善DLC薄膜的结合状况,并且经过20%的拉伸变形后,DLC薄膜完整,耐蚀性优于未表面处理的316L不锈钢.以上研究结果表明,磁过滤阴极真空弧源方法制备DLC薄膜与316L结合强度高,可以有效的提高316L的耐腐蚀性,是一种具有应用前景的血管支架表面改性方法.     

过渡层对TC4钛合金基类金刚石多层薄膜磨损特性的影响

在钛合金(TC4)表面制备类金刚石(DLC)薄膜是提高其耐磨损性能和使用寿命的一种有效方法。本文采用磁过滤阴极弧源技术在钛合金表面上制备软硬相间的类金刚石多层薄膜、Ti和Ti/TiC过渡层组成的类金刚石多层薄膜。利用光学显微镜和扫描电镜分析多层膜表面外观形态,并使用台阶仪、纳米压痕仪、摩擦实验机等分析多层膜的残余应力、纳米硬度、膜基结合力和摩擦磨损特性。研究结果表明：DLC多层薄膜的残余应力均低于单层DLC薄膜,残余应力从12.63 GPa降低到6.21 GPa,增加Ti/TiC过渡层的DLC多层薄膜的残余应力最小。压痕结合力研究结果表明,加入Ti/TiC过渡层的DLC多层薄膜的结合状况得到了显著提高。Ti/TiC过渡层构成的类金刚石多层薄膜,有较大的硬度和良好减摩耐磨性能。试验结果将为TC4钛合金基体上制备硬质耐磨损DLC多层薄膜提供技术方案和理论依据。     

钛过镀层对类金刚石薄膜的膜基结合力以及摩擦学性能的影响

采用双弧磁过滤真空弧源,在钴铬合金基体上成功地沉积了Ti/DLC多层膜,其钛过渡层利用不同的负偏压来制备.利用纳米划痕法来评价薄膜的膜基结合力,类金刚石薄膜的摩擦性能在销盘式摩擦磨损试验机进行测试.划痕法的结果均表明,增加钛的过镀层后薄膜的结合状况得到明显的改善,纳米划痕法测试膜基结合力表明其临界载荷可达到740mN,摩擦磨损实验可以看出镀膜后的样品的摩擦系数均在0.1左右,DLC薄膜可极大地改善钴铬合金的摩擦学性能.     

TiC/DLC多层膜的制备及组织形态

本文采用非平衡磁控溅射沉积技术,以甲烷气体为碳源,99.99%Ti为靶材制备了TiC/DLC多层膜。利用X射线衍射仪、电子显微镜、俄歇电子能谱仪和拉曼光谱仪等对TiC/DLC多层膜的组织、结构、形态及成分进行了分析。结果表明:Ti与C结合生成TiC晶相,过渡层中TiC相呈柱状晶生长,多层膜中的TiC分层以岛状模式生长,DLC分层以层状模式生长,TiC/DLC膜层中含有金刚石成分。TiC/DLC的多层结构受沉积参数的影响,当分层的沉积时间少于1 min时,很难获得清晰的层状结构薄膜,膜中Ti的含量随Ti靶电流的增加而增加;过渡层的引入,提高了膜与基体的结合力,并且过渡层的厚度增加,TiC/DLC膜层同基体之间的结合力增强。     

中频磁控溅射沉积DLC/TiAlN复合薄膜的结构与性能研究

采用中频非平衡磁控溅射沉积工艺,并施加霍尔离子源辅助沉积,在高速钢W18Cr4V及单晶硅基体上制备了梯度过渡的DIE/TiAlN复合薄膜.利用扫描电镜(SEM)、X射线光电子能谱仪(XPS)、显微硬度计、摩擦磨损仪等分析检测仪器对DLC/TiAlN复合薄膜的表面形貌、晶体结构、显微硬度、耐磨性等性能进行了检测分析.实验及分析结果表明:DLC/TrAlN薄膜平均膜厚为1.1μm,由于薄膜中的Al含量较多,使得复合薄膜的表面比DLC薄膜的表面要粗糙一些;通过对复合薄膜表层的XPS分析可知,ID/IG为2.63.由XPS深层剖析可知,DLC/TiAlN薄膜表层结构与DLC薄膜基本相同,里层则与TiAlN薄膜相似.在梯度过渡膜中,复合膜层之间的界面呈现为渐变过程,结合的非常好.DLC/TiAlN薄膜的显微硬度为2030 HV左右.与DLC薄膜显微硬度接近,低于TiAlN薄膜的显微硬度.但是DLC/TiAlN薄膜的耐磨性要好于TiAlN薄膜和DLC薄膜;DLC/TiAlN薄膜的耐腐蚀性能略好于DLC薄膜.     

铝基复合材料表面多层复合厚膜的研究

对含50%AlN颗粒的铝基复合材料进行预处理后,在其表面依次采用浸锌化学镀镍工艺制备Ni-P过渡层,采用脉冲偏压磁过滤多弧离子镀工艺沉积硬质Ti/TiN调制周期膜,采用脉冲等离子体化学气相沉积工艺制备含氢类金刚石(DLC)膜等工艺最后形成了多层复合薄膜体系。利用X射线衍射仪、扫描电子显微镜、光谱仪、原子力显微镜、微载荷显微硬度仪、摩擦磨损试验机等设备分析了复合薄膜的组织结构、膜层形貌、截面形貌、显微硬度和摩擦系数等性能特点。测试表明:铝基复合材料/Ni-P层/Ti/TiN调制周期膜/含氢DLC膜这一梯度膜系具有结构交替变化,相邻界面形成混合层,性能梯度分布,硬度逐渐增加,摩擦系数小的特点。该复合工艺能够有效地解决铝基复合材料上制备硬质厚膜的热适配和晶格错配度大的难题,制备薄膜具有良好的膜基结合性能。     

H13钢离子渗氮(PN)与类金刚石(DLC)复合处理的摩擦磨损性能研究

采用阳极层流离子源与非平衡磁控溅射结合的沉积方法在H13钢基体表面沉积出类金刚石膜(DLC),并对H13钢经不同表面预处理对后沉积的DLC膜的摩擦学性能进行了对比研究.结果表明:DLC膜结构致密,且DLC膜与梯度过渡层及基体三者之间结合牢固;H13钢经离子氮化后,梯度过渡层与氮化层间结合紧密,提高了膜与基体的承载能力;在保持相同摩擦速率的条件下,摩擦系数随着载荷的增加先增大后减小;H13钢离子渗氮处理后沉积的DLC膜其摩擦系数远小于未采用离子渗氮处理沉积的DLC薄膜.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

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.     

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.……     

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...     

Flow calorimeter for enthalpy increment measurements on condensed gases

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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

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.     

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.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...