激光表面重熔等离子喷涂陶瓷涂层的研究与发展

总结了等离子喷涂陶瓷涂层的缺欠以及激光重熔等离子喷涂陶涂层所存在的问题,在分析问题产生原因的基础上,提出了防止激光重熔等离子喷涂陶瓷涂层裂纹,气孔和剥等问题的同时指出了激光了涂陶瓷涂层的发展趋势。     

TiAl合金表面激光重熔热障涂层组织及抗高温氧化性能

为了进一步提高TiAl合金表面等离子喷涂ZrO2-7%(质量分数)Y203热障陶瓷涂层的性能,采用激光重熔工艺对涂层进行处理,研究了激光重熔对涂层微观组织和抗高温氧化性能的影响.用扫描电镜(SEM)分析了涂层形貌和微观结构,同时对其抗高温(850℃)氧化性能进行了考察.结果表明,等离子喷涂热障陶瓷涂层呈典型的层状堆积特征,有一定的孔隙且分布有微裂纹;经过激光重熔处理后,陶瓷涂层片层状组织得以消失,致密性提高,获得了基本没有裂纹等缺陷的重熔层;整个重熔层包括界面没有明显特征的平面晶和上部沿热流方向生长的柱状晶组织.等离子喷涂热障涂层具有较好的抗高温氧化性能,经过激光重熔后可进一步提高其抗高温氧化能力.     

激光-等离子束复合制备热障涂层高温性能试验研究

在GH536高温合金基材上,采用矩形积分透镜,激光重熔等离子喷涂NiCrAlY/8YSZ热障涂层。1050℃的静态氧化试验和热震试验的结果表明:激光重熔可以改善热障涂层的抗氧化性能,能量密度33J·mm-2的激光重熔试样具有高于等离子喷涂试样的热震寿命,氧化阻力的改善与重熔层致密组织有关,微细网状裂纹释放热震应力的作用是热震寿命提高的主要原因。     

激光重熔过程中激光功率对镁合金表面等离子喷涂YSZ涂层结构的影响

为了提高铝合金的综合性能,采用等离子喷涂技术在AZ31B镁合金表面沉积氧化钇部分稳定二氧化锆(YSZ)涂层,并采用二氧化碳激光器对涂层表面进行重熔处理,利用X射线衍射仪、扫描电镜及三维激光成像显微镜研究了重熔激光功率对涂层物相组成、组织结构及表面形态的影响规律。结果表明:YSZ涂层在激光表面重熔过程中保持了相结构的稳定性,即喷涂态及激光重熔后的涂层均由非转变型的四方相组成;随激光功率的增大,重熔区厚度不断增加,且喷涂态涂层的层状组织结构在激光重熔后消失,气孔率降低;在激光处理过程中,产生了大量的内应力,导致纵向(垂直于涂层表面)裂纹的萌生及扩展;涂层表面粗糙度随激光功率的增加而不断降低,并且在功率低于400 W时下降更明显。     

常规和纳米ZrO_2-7%Y_2O_3等离子喷涂热障层及其激光重熔后的抗热震性能

为了探讨激光重熔对等离子喷涂常规和纳米热障涂层(TBCs)的影响,采用等离子喷涂工艺在γ-TiAl合金表面制备了常规和纳米ZrO2-7%Y2O3TBCs,并对其进行激光重熔处理,研究了等离子喷涂常规TBCs、激光重熔-等离子喷涂常规TBCs、等离子喷涂纳米TBCs及激光重熔-等离子喷涂纳米TBCs 4种涂层在850℃下的抗热震性能。结果表明:4种TBCs热震失效次数依次为73,118,146,163次,相应的热震破坏形式分别为整体剥落、局部剥落、边角剥落和局部剥落;纳米结构有利于提高涂层的抗热震性能;激光重熔在一定程度上改善了等离子喷涂层的抗热震性能。     

金属雾化喷嘴表面热障涂层结构特征研究

采用5KW连续CO2激光器对经等离子喷涂的NiCoCrAlY结合层和ZrO2陶瓷层进行二次重熔处理，并利用金相显微镜，扫措电镜和电子探针对激光熔敷涂层进行了显微结构和元素分布观察与测试，结果表明：激光熔敷涂层中基体对NiCoAlY合金层产生稀释，形成成分和组织偏析。加入了TiO2-Al-Ti添加剂的ZrO2陶瓷层激光重熔后得到了无裂纹的定向生长柱状晶，并且呈现一次枝晶平均间距为2．3μm的表层和平均间距为3．8μm的次表层结构。     

涂层

20010601 等离子喷涂Ni-Cr-B-Si及激光重熔涂层的耐磨性 ──Liang G Y. Surface & Coatings Technology, 2000,12 7(2～3):233(英文)在Al合金上等离子喷涂Ni-Cr-B-Si和Ni-Cr-B-Si+WC,用CO_2激光器重熔合金涂层, 对比研究了激光重熔涂层和等离子喷涂涂层的耐磨性,用SEM分析了磨损形貌。结果表明, 激光重熔涂层和等离子喷涂涂层均具有良好的耐磨性,激光重熔Ni-Cr-B-Si涂层耐磨性 最好,优于等离子喷涂Ni-Cr-B-Si涂层;等离子喷涂Ni-Cr-B-Si+WC涂层的耐磨性优 于等离子喷涂Ni-Cr-B-Si涂层,但激光重熔并未改变二种涂…     

等离子喷涂涂层重熔后处理的研究现状与展望

鉴于喷涂涂层存在的较高孔隙率和较大残余应力而常常需要进行适当的后处理,介绍了等离子喷涂涂层的几种重熔后处理技术,对各种处理方式进行归纳总结,并分析了各种处理方式的优缺点。对未来喷涂涂层重熔后处理技术进行展望,提出了根据涂层性质选择合适后处理方式、进一步优化后处理工艺、建立涂层寿命监测系统并进行涂层失效预测等提高涂层使用性能的建议。有关研究说明：喷涂涂层的激光重熔后处理技术能让涂层与基体间由机械结合为主转为以冶金结合为主,可有效增强涂层的硬度、耐磨性、耐腐蚀性及抗高温氧化性等,且其选材的来源广泛,热影响区和工件的变形量较小,但激光重熔时涂层易出现裂纹,因此不宜对大面积涂层进行激光重熔后处理;喷涂涂层的感应重熔后处理技术热影响区较小,可消除涂层中的气孔和微裂纹,有效增强涂层的耐磨性和耐腐蚀性,但感应重熔过程会受到涂层自身电阻率的限制而降低重熔后处理的效率;喷涂涂层的电子束重熔后处理技术适用范围广,成本较低,无污染,可有效提高涂层的硬度、耐磨性和抗氧化性能,减少涂层间的气孔,降低涂层表面的粗糙度,但电子束重熔过程对工作环境要求较高;喷涂涂层的火焰重熔后处理技术操作简单、成本较低,喷涂涂层的钨...     

TiAl合金表面激光重熔等离子喷涂MCrAlY涂层研究

为了进一步提高TiAl合金表面等离子喷涂MCrAlY涂层的高温氧化性能,采用激光重熔工艺对涂层进行处理,研究了激光重熔对涂层微观组织及抗氧化性能的影响.用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析了涂层氧化前后的表面形貌、微观组织和相组成.结果表明:经过激光重熔处理后,涂层片层状组织得以消失,致密性提高,消除了喷涂层的大部分孔洞、夹杂等缺陷,同时使Al元素在涂层表面的重新分布,形成了Al的富集区;等离子喷涂MCrAlY层能显著提高TiAl合金的抗高温氧化性能,经过激光重熔后可进一步提高其抗高温氧化性能.     

高温合金表面激光熔敷热障涂层组织结构与氧化性能

采用5KW连续CO2激光器对Ni基高温合金上二次重熔NiCoCrAlY和ZrO2陶瓷层进行了研究。结果表明，激光快速熔化和凝固获得定向外延生长，紧密堆积的柱状晶氧化锆陶瓷层。NiCoCrAlY结合层与柱状晶之间存在氧化铝层，保证了柱状晶与NiCoCrAlY层的联结。扫描电镜和电子探针联合分析发现，氧化锆层与NiCoCrAlY结合层，结合层与基体间均为冶金结合，采用化学改性氧化锆消除了涂层裂纹。高温氧化性能测试得出激光重熔试样氧化动力学近似地遵守物线速度方程，在1200℃，空气下激光熔敷TBCs抗氧化性明显高于等离子喷涂TBC。     

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.     

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...     

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.     

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.     

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.     

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