Ni/ZrO2纳米复合刷镀层的抗高温氧化性

采用电刷镀技术制备了Ni/ZrO2纳米复合镀层。利用扫描电子显微镜、X射线衍射等手段,研究了Ni/ZrO2纳米复合刷镀层的组织和抗高温氧化性能,并与快速镍镀层进行对比分析。结果表明,与快速镍镀层相比,Ni/ZrO2纳米复合镀层的表面形貌更为平整致密,晶粒尺寸明显减小;在800℃氧化后复合镀层晶粒依然较快速镍镀层细小、均匀,氧化增重速率明显低于快速镍镀层;X射线衍射分析表明,Ni/ZrO2复合镀层的氧化程度较轻,镀层中仍然存在大量的Ni相。     

电沉积RE-Ni-W-B-B4C-MoS2复合镀层的性能研究

研究了RE-Ni-W-B-B4C-MoS2复合镀层在不同氧化温度和时间下的抗高温氧化性，结果显示：当温度小于800℃时，RE-Ni-W-B-B4C-MoS2复合镀层被氧化的程度较小；温度超过800℃，氧化膜的增重呈直线增加，RE-Ni-W-B-B4C-MoS2复合镀层的硬度随着热处理温度的升高而增加，当热处理温度达到400℃时，复合镀层的硬度升到极大值（1368HV）；若继续升高温度，镀层硬度逐渐降低，RE-Ni-W-B-B4C-MoS2复合镀层的耐磨性经400℃热处理后最好，工艺条件对RE-Ni-W-B-B4C-MoS2复合镀层的表面形貌影响较大，随着电流密度或镀液温度的升高，复合镀层结晶粗，晶粒大；反之，镀层结晶细，表面晶粒细小。RE-Ni-W-B-B4C-MoS2复合镀层的镀态下以非晶态为主，部分已晶化，当经500℃热处理后，复合镀层已晶化；经800℃热处理后，CeO2和B4C仍以化合物的形式存在，由此可以说明，CeO2和B4C的加入，可以提高RE-Ni-W-B-B4C-MoS2复合镀层的热稳定性。     

Ni/ZrO_2复合镀层电沉积行为与耐高温氧化性能的研究

通过电化学试验、高温氧化试验、扫描电镜及X 射线衍射 ,研究了电沉积Ni/ZrO2 复合镀层的电化学行为和添加微粒对镍镀层高温抗氧化性能和组织结构的影响。研究结果表明 ,在瓦特 (Watts)镀液中加入ZrO2 微粒使电镀时阴极电流密度明显降低 ,阴极电位与时间 (E t)、阴极电流对时间 (I t)的关系曲线变化趋势不大 ,但I t曲线抖动加快 ;高温氧化试验结果表明 ,ZrO2 微粒可以使复合镀层的高温抗氧化能力明显提高 ;Ni/ZrO2 复合镀层与瓦特镍镀层的高温氧化规律基本满足W =ktn;扫描电镜能谱分析则证实 :在 80 0℃高温氧化过程中 ,明显存在铜向镍镀层中的扩散 ,这可能有利于增强镀层与基底之间的粘合。X 射线衍射表明 ,在高温氧化时 ,镀层表面主要生成NiO产物。     

Ni/ZrO2梯度镀层高温氧化性能及热应变特性

采用复合电沉积法制备Ni/ZrO2梯度镀层.SEM测试表明,沿镀层生长方向,ZrO2含量由0逐渐增加到21%(体积分数),呈梯度分布;高温氧化实验结果表明,梯度镀层在800℃处理24h后氧化增重仅为纯镍镀层的1/6,氧化处理并未改变镀层中ZrO2微粒的梯度分布.结构分析表明,ZrO2微粒的掺杂使梯度镀层晶粒细化,结晶细致,可阻止高温氧化时氧原子向金属内部扩散.弥散分布的ZrO2对金属镍高温氧化时具有活性元素效应,可阻止Ni的短路扩散,降低氧化增重速率.因此,Ni/ZrO2梯度镀层具有优良的高温氧化性能,可用于高温氧化气氛之中.热应变特性研究表明,沿镀层厚度方向,热应变变化平缓,有效地缓解了界面处材料热失配,从而降低了材料的热应力.     

稀土La对渗铝层及其抗高温氧化性能的影响

稀土元素La对传统的铝层的结构及其抗高温氧化性能的影响机理尚未充分定型.以低碳钢为基体,预置纯镍和Ni-La2O3复合电镀层,采用固体粉末法进行渗铝,对渗铝试样进行高温氧化试验.用光学显微镜(OM)、扫描电镜及能谱(SEM/EDAX)等方法对试样进行了分析,发现稀土元素La促进了渗铝的过程,使渗铝层中铝含量较高,质量分数为35%,并且渗层组织细小均匀,表面质量好;高温氧化后,Ni-La镀层渗铝层表面形成的氧化膜薄而致密,氧化增重较小,具有较好的抗高温氧化性能.     

Ni／ZrO2复合镀层电沉积行为与耐高温氧化性能的研究

通过电化学试验,高温氧化试验、扫描电镜及Ｘ－射线衍射,研究了电沉ｉ／ＺｒＯ２复合镀层的电化学行为和添加微粒对镍镀层高温抗氧化性能和组织结构的影响,研究结果表,在瓦特镀液中加入ＺｒＯ２微粒使电镀时阴极电流密度明显降低,阴极电位与时间、阴极电流对时间的关系曲线趋势不大,但Ｉ－ｔ曲线抖动和加快;高温氧化试验结果表明,ＺｒＯ２微可以使复合镀层的高温抗氧化能力明显提高;Ｎｉ／ＺｒＯ２复合镀层与瓦特镍镀层的高     

氩气预热处理对Ni—B4C—RE复合镀层高温氧化特性的影响

本文系统地研究了在氩气中预热处理对电沉积Ｎｉ－Ｂ４Ｃ－ＲＥ复合镀层在８００℃大气中氧化特性的影响。实验证明，经氩气预热处理，镀层中原Ｂ４Ｃ微粒逐渐分解，消失，形成了Ｎｉ３Ｂ新相，这种镀层再经氧化，能生成抗氧化能力较强的均相Ｎｉ３Ｂ２Ｏ６氧化膜，稀土加入镀层后，在氩气预热处理过程中，能促进新相的生成，从而进一步提高了镀层抗高温氧化能力。     

结晶器表面电沉积RE-Ni-W-P-B4C镀层性能的研究

在新开发的RE-Ni-W-P-B4C结晶器表面镀层的基础上,研究了热处理工艺对此复合镀层的硬度、物相的影响,并借助氧化失重试验分析了复合镀层的高温抗氧化性能.采用HM-114型显微硬度仪测定镀层的硬度;采用Phlip X射线衍射仪进行镀层物相分析;采用电阻炉对不同镀层试样进行氧化.结果表明:热处理温度＜400℃时,随着温度的升高镀层硬度增加,＞400℃时,硬度变化不大;当热处理温度达500℃、时间为3 h时硬度达到最大值,为1 236.4 HV,此时镀层主要为晶态物相:CeO2、Ni、W、P、Ni3P、Ni3B.对比了不同镀层在不同温度下的抗氧化性能,发现RE-Ni-W-P-B4C镀层在＜650℃时有很好的抗氧化性能.     

Cu-Zr合金基体上的复合镀层的性能研究

利用复合电沉积的方法在Cu-Zr合金基体上沉积出含ZrO2微粒的Ni-ZrO2复合镀层,研究了镀层中的ZrO2微粒含量与镀液中ZrO2微粒含量的关系以及Ni-ZrO2合度层在高温条件下的抗高温氧化笥能和耐腐蚀性能,结果表明：Cu-Zr合金基体上镀覆的Ni-ZrO2复合镀层的抗高温气化性能和耐腐蚀性能得到了很大的提高。     

铝材脉冲电镀Pb-WC-CeO_2复合层的电化学性能

为了探究脉冲电镀铝基Pb-WC-CeO2复合镀层的电化学性能,考察了正向脉冲参数(平均电流密度Jm、占空比r及正向脉冲工作时间ton)及温度对镀层在锌电解液中作阳极时的耐蚀性及析氧动力学参数的影响。结果表明:当Jm=120 mA/cm2,r=20%,ton=200 ms、θ=50℃时,Pb-WC-CeO2复合镀层具有较强的耐蚀性;将其用作锌电解的阳极,槽电压最小,能耗小,有最好的电催化活性,且优于直流镀层。     

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.……     

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.……     

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 ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.