Q235钢表面双层辉光离子强化层摩擦磨损性能

在真空容器中,设置提供含有欲渗合金元素Mo,Cr的供给源和被渗Q235钢试样,利用双层辉光离子渗金属技术,在试样表面进行Mo-Cr共渗,之后经渗碳、淬火及回火复合处理形成强化层.Mo-Cr共渗层厚度在100μm以上,表面Mo含量可达20%(质量分数,下同),Cr含量达到10%.复合处理后表面硬度达到1300HV0.025.M-200磨损试验机磨损实验表明,摩擦因数平均在0.1左右,平均相对耐磨性是GCr15钢经渗碳、淬火及回火后的2.25倍.     

深冷处理对碳钢表面Mo-Cr合金层摩擦性能的影响

介绍了一种在Q235钢表面进行等离子合金化及热处理工艺,获得表面高性能强化层的技术方法.通过该技术方法的处理,使Q235钢表面含有Mo,Cr,C合金元素,成分达到或接近冶金高速钢.该工艺技术的基本原理是在真空容器中,利用辉光放电的溅射现象,首先在Q235钢表面渗入合金元素Mo,Cr,表面含量分别达到12%(质量分数,下同)和4%左右,随后进行超饱和渗碳,使表面含碳量达到2.0%以上,合金化层成分接近钼系高速钢.合金层中的碳化物细小、均匀、弥散,无粗大的共晶莱氏体组织.Q235钢表面合金化后分别采用淬火 低温回火,淬火 2h深冷处理 低温回火两种工艺.结果发现,经深冷处理的试样表面硬度达到1600HV,明显高于未经过深冷处理试样的表面硬度.摩擦磨损实验表明,经深冷处理试样的滑动摩擦系数较未经深冷处理试样的要小,经深冷处理试样的耐磨性是未经深冷处理的1.6倍.     

Q235钢表面TiN陶瓷化与Cr-Mo共渗表面强化耐腐蚀性能研究

介绍了一种在Q235钢表面用等离子直接复合渗镀合成氮化钛的方法.该工艺方法形成的组织是Ti固溶体扩散层上分布弥散细小氮化钛颗粒和表面氮化钛沉积层,沉积层与渗层和基体为冶金结合,不会产生剥落.渗镀层表面硬度1600～3400HV.X射线衍射结果表明,渗镀层表面为纯氮化钛层,(200)晶面的衍射峰最强,具有明显的择优取向.在Q235钢表面进行双层辉光离子铬钼共渗,表面Mo含量达到4%(质量分数,下同),Cr含量达到12%.然后进行超饱和渗碳,表面含碳量达到2.0%以上,超过平衡碳计算值.随后进行淬火 低温回火热处理,使表面合金层获得马氏体基体上均匀分布的细小弥散碳化物组织,没有共晶莱氏体.经X射线衍射分析,渗层碳化物类型为M23C6,M6C和M2C,尺寸小于5μm.表面硬度达到1100HV.将等离子复合渗镀合成氮化钛试样与双层辉光离子渗铬试样,在10%硫酸、5%的盐酸、3.5%NaCl水溶液和H2S富液(含H2S 5～8g/L,NH3·H2O20g/L)中,进行电化学腐蚀实验.结果表明,渗镀试样比铬钼共渗试样耐蚀性能分别提高了84,11.67,1.15,21.15倍.     

20CrV钢机用锯条齿部表面强化组织的研究

本文介绍了２０ＣｒＶ钢机用锯条经渗金属、渗碳、淬火及回火的表面强化处理工艺，并对强化后锯条齿部碳化物、相结构进行了组织分析和Ｘ射线检测。研究结果表明，齿部组织状态及相结构已接近高速钢，经切削试验，性能达到高速钢要求。     

15CrNi4Mo钢渗碳及热处理工艺研究

研究了表面碳含量和热处理工艺对15CrNi4Mo钢渗碳层的影响,分析了渗层显微组织和硬度分布。结果表明:渗碳后表面碳含量为0.90%时,在805℃淬火310℃回火后,渗碳层组织为细针状回火马氏体、残余奥氏体和少量碳化物,心部组织为回火马氏体及少量铁素体,能够满足使用要求。     

双辉等离子表面Ni-Cr合金渗层的组织及耐蚀性能研究

采用双层辉光等离子表面冶金技术在Q235钢表面制备Ni-Cr合金渗层,对合金渗层的组织特征、成分和耐蚀性能进行了研究.结果表明:Ni-Cr合金渗层与基体呈现良好的冶金结合状态;渗层中Ni,Cr元素含量由表及里逐渐减少,厚度约为30μm,渗层主要物相为Ni2.9Cr0.7Fe0.36.电化学极化试验表明经Ni-Cr共渗处理后试样的耐蚀性明显优于基材,且Ni-Cr合金渗层的保护效率高达99.7468%,而孔隙率仅有0.2%.     

等离子渗铬及复合强化处理提高耐磨性能的研究EI

利用铬与-αFe无限互溶,含铬的共晶碳化物与二次碳化物形成机理不同,首先在Q235钢和45钢表面渗入合金元素铬,形成高铬合金扩散层,表面含铬量达到40%(质量分数,下同)以上,并在一定范围内使表面合金层铬含量呈梯度分布。利用铬是碳化物形成元素,进行等离子渗碳,因为碳化物形成温度低,在高铬合金层中固体形核长大,所形成的含铬碳化物弥散、细小、均匀。虽表面含碳量达2.8%以上,但是没有共晶碳化物。经淬火及回火处理,表面硬度在HV1800以上。磨损实验表明:与对磨淬火GCr15钢相比,耐磨性能提高7倍以上。     

不同电源等电位离子钨钼共渗的研究

利用脉冲单电源和直流单电源,分别在Q235钢表面进行等离子钨钼共渗.通过对不同电源钨钼共渗试样的渗层组织、渗层成分分布、晶体结构、渗层硬度分布的检测和比较,分析了2种电源对等离子钨钼共渗的影响.结果表明,利用单一电源均可在Q235钢表面形成明显反应扩散层;在相同工艺下,采用脉冲电源所得到的试样渗层厚度较采用直流电源的渗层厚度增加了18.1%;脉冲电源试样表面W、Mo含量(质量分数,下同)分别约为8.4%和9.8%,直流电源试样表面W、Mo含量分别为8.2%和8.9%,可见2种电源渗层表面含W、Mo量相差不大;2种电源渗层相结构均为Fe_7W_6和Fe_3Mo金属间化合物相;钨钼共渗后渗层硬度提高不明显.     

Q235低碳钢等离子体电解硼碳共渗处理及性能分析

采用液相等离子体电解渗方法对Q235低碳钢进行硼碳共渗(PEB/C)处理,研究了Q235低碳钢表面硼碳共渗层的形貌、结构和显微硬度。评估了PEB/C处理前后Q235钢的电化学腐蚀性能,以及以GCr15钢球作为摩擦副在不同载荷条件下PEB/C渗层的摩擦磨损特性。结果表明,经过PEB/C处理后(330V/30min),形成厚度约为20μm并主要由Fe2B相组成的渗硼层。PEB/C处理轻微提高了Q235钢的耐腐蚀性能,但明显降低了Q235低碳钢与GCr15钢球对磨的摩擦因数和磨损率。当载荷为5N时,PEB/C样品的摩擦因数和磨损率分别是Q235钢基体的1/4和1/59。     

等离子表面冶金Cr、Mo高速钢的研制

介绍了一种在铁碳合金表面进行等离子合金化及热处理的技术.在低碳钢表面渗入合金元素Cr、Mo,表面含量分别达到4%和12%左右,随后进行超饱和渗碳,使表面含碳量达到2.0%以上,合金化层成分接近钼系高速钢.形成的碳化物细小、均匀、弥散,没有粗大的共晶莱氏体组织.试样经深冷处理后表面硬度达到1600Hv.经X射线衍射分析,表面碳化物晶体结构相主要是有M23C6、M6C和M2C,尺寸≤1μm.     

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.     

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.     

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.……     

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.……     

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.     

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.