Ti_2AlNb基合金表面磁控溅射Al/Al_2O_3薄膜及扩散处理对其抗高温氧化性能的影响

为提高Ti2Al Nb合金的抗高温氧化性能,在Ti2AlNb合金表面磁控溅射Al/Al2O3薄膜,于真空退火炉内对其进行600℃,1 h扩散处理后,分别在650,750,850℃下氧化100 h。利用XRD,SEM,EDS技术对基体和扩散试样的相组成、微观形貌进行了分析;研究了Al/Al2O3薄膜扩散层的抗高温氧化性能及扩散处理对Al/Al2O3薄膜氧化动力学曲线的影响。结果表明:Al/Al2O3薄膜扩散层的氧化行为受氧离子渗入薄膜运动过程的控制,在高温条件下表层形成连续致密的Al2O3膜,使薄膜扩散层的氧化系数远低于基体,并且次表层的富铝相能有效阻止氧离子扩散通道的形成,减少基体与氧化性气体接触,从而显著提高Ti2Al Nb基合金的抗高温氧化性能。     

Ti0.7Al0.3N涂层的抗NaCl和水蒸气腐蚀行为

用电弧离子镀方法在1Cr11Ni2W2MoV不锈钢表面制备Ti0.7Al0.3N涂层,研究了涂层在450℃空气中恒温氧化行为和在固态NaCl和水蒸气综合作用下的腐蚀行为.结果表明:Ti0.7Al0.3N涂层在空气中均具有优良的抗氧化能力,而不锈钢在固态NaCl和水蒸气综合作用下的腐蚀严重,施加Ti0.7Al0.3N涂层显著地提高了不锈钢基体的抗腐蚀性能.1Cr11Ni2W2MoV不锈钢由于生成内层富Cr,外层富Fe的疏松氧化物,其在固态NaCl和水蒸气综合作用下发生严重的腐蚀,而Ti0.7Al0.3N涂层生成致密的Al2O3和TiO2的混合物,使其具有良好的抗氧化和腐蚀性能.     

0Cr18Ni10Ti不锈钢热浸镀铝及高温扩散后的高温氧化行为

为提高0Cr18Ni10Ti不锈钢的抗高温氧化能力,采用熔剂法在0Cr18Ni10Ti不锈钢表面制备热浸镀铝层,并经950℃、2 h高温扩散。采用SEM、EDS对热浸镀铝高温扩散试样及不锈钢试样900℃氧化不同时间的表面、截面进行了形貌观察及成分分析。结果表明:镀铝高温扩散试样的氧化动力学曲线较平缓且氧化增重较小;0Cr18Ni10Ti不锈钢经900℃、100 h氧化后表面主要由Fe2O3组成,氧沿晶界向内扩散产生内氧化;镀铝高温扩散试样900℃氧化期间,表面主要由Al2O3氧化膜组成,有效地阻止了合金元素与氧的互扩散,Ni元素在Fe Al层与Al固溶层富集阻碍了Fe Al合金层Al向基体扩散,使镀铝高温扩散试样Fe Al合金层经900℃、100 h氧化后Al元素贫化量较少。镀铝高温扩散试样900℃、100 h下的抗氧化性能优于0Cr18Ni10Ti不锈钢。     

Ti3SiC2陶瓷材料的制备及抗烧蚀行为

以固溶少量Al的Ti3SiC2粉体为原料,采用热压烧结工艺制备出致密度大于99％的Ti3SiC2陶瓷块体材料,其硬度、抗弯强度和断裂韧度分别为775HV,520.46 MPa和7.62 MPa·m1/2.对Ti3SiC2块体在无冷却条件下进行抗氧乙炔焰烧蚀实验,结果表明:烧蚀10 s内Ti3SiC2陶瓷保持表面平整,烧蚀25 s内样品未出现宏观裂纹.SEM和XRD观察分析表明,Ti3SiC2陶瓷在高温乙炔焰和氧气的高热流冲击作用下,表面发生分解和氧化,Si和C被氧化为Si-O化物和C-O化物气体逸出,Ti元素被氧化成高温稳定的TiO2金红石相覆盖在表面;氧化层呈3层结构分布,最外层为结构疏松的TiO2,次表层则为TiO2和Al2TiO5组成的致密复合层,内氧化层为致密Al2O3富集层,Al2O3来源于固溶在原料Ti3SiC2中Al元素的氧化,并在高温下与TiO2反应生成了Al2 TiO5.具有高黏度和高熔点的Al2O3富集层可以有效阻碍O2和热流向基体的扩散,从而降低基体的氧化速率,提高Ti3SiC2材料的抗烧蚀性能.     

Fe_3Al高温腐蚀与防护机理

采用连续氧化和非连续氧化两种方式,对比研究了Fe_3Al在800～1200℃空气中的氧化规律和机制。分析了Fe_3Al在非连续氧化过程中发生Pest的机制。首次发现了Fe_3Al在1000℃氧化/硫化环境中的灾难性腐蚀现象,提出了提高Fe_3Al抗高温氧化/硫化的关键在于促进合金中Al的扩散,避免基体中严重贫Al区的形成;促进Al选择氧化,提高氧化膜的塑性和粘附性。 研究了电沉积-反应烧结氧化物薄膜改善合金的抗氧化性能和氧化膜的粘附性的机制。离子注入Y改善了氧化膜的粘附性,提高了Fe_3Al的抗高温氧化性能;但同时促进了S向氧化膜/基体界面的扩散,因而不能有效地提高Fe_3Al的抗高温氧化/硫化性能。包埋渗Al改善了基体自愈氧化膜的能力,提高了Fe_3Al的抗高温腐蚀性能,但存在氧化膜不致密、易脱落等缺点。首次应用高能量密度等离子体对Fe_3Al进行了微晶化处理,发现表面微晶化后氧化形成了塑性和粘附性皆极佳的微晶氧化膜,使Fe_3Al在高温氧化/硫化环境中的抗腐蚀性可与在空气中的抗氧化性相媲美。指出了在不同文献中对晶粒细化的作用得出相反结论的原因。提出了晶粒度等级影响氧化膜性质的新机制。首次提出微晶合金氧化动力学应服从四次方规律,导出了相应的公式,并得到实验结果的一致验证。     

涂层结构对Ti-Al-N涂层氧化行为的影响

采用多弧离子镀技术及TiA合金靶,在SKH51高速钢基体上沉积了Ti1-xAlxN单层构型涂层和TN/Ti1_xAlxN复合多层构型涂层,分析其高温氧化行为.用扫描电镜、X射线衍射、电子探针等手段表征了涂层氧化后的组织结构和元素分布.试验发现,基体Fe元素扩散到涂层表面意味着SKH51涂层试样剧烈氧化阶段的开始.当涂层的构型相同时,涂层的抗氧化性能随着涂层中铝含量增加而单调增加.但对于TiN/Ti0.33Al0.67N复合多层构型涂层,其抗氧化性则比Ti0.33Al0.67N单层构型涂层差,高于铝含量基本相同的Ti0.67A0.33N单层构型涂层.空气中800℃恒温退火,TiN/Ti0.33 Al0.67N涂层出现严重氧化的时间是43h,Ti0.33Al0.67N、Ti0.67Al0.33N涂层分别为53 h和11h.因此,Ti-Al-N涂层的抗氧化性不仅同涂层中铝含量有关,涂层构型也起着重要用.     

FeCrNi合金表面MnO薄膜的制备及其抗渗碳性能

为了提高铁铬镍合金(Fe Cr Ni)的抗渗碳性能,在Fe Cr Ni合金表面电镀金属Mn薄膜,然后利用低氧分压氧化法在Fe Cr Ni合金表面制备Mn O薄膜。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)等研究Fe Cr Ni合金表面Mn O薄膜的组织结构、形貌、薄膜与基体界面扩散层情况及Mn O薄膜的抗渗碳性能。结果表明:经低氧分压氧化法处理后,金属Mn薄膜完全氧化为Mn O薄膜,且在Mn O薄膜和基体之间形成扩散层,扩散层中出现了Mn Cr_2O_4尖晶石相,Mn O薄膜具有明显的抗渗碳效果。     

喷丸对TP304H钢高温水蒸气氧化行为的作用

研究了表面喷丸形变处理对TP304H钢在610～770℃水蒸气中的氧化行为的影响,采用SEM、EDX和EPMA分析了不同喷丸强度对合金水蒸气氧化65 h的氧化膜形貌、结构和表面合金元素的影响.结果表明:表面喷丸形变可有效减缓氧化动力学速度,在0.5 MPa喷丸强度和730℃条件下提高抗氧化性能的效果最好,表面氧化膜颗粒得到细化,膜中Cr相对浓度明显提高,氧化膜物相构成由纯Fe和Fe、Cr混合氧化物转变为Cr2O3.分析认为:表面喷丸形变处理增加了合金表层区域的位错、空位等缺陷浓度,提高了氧化初期的形核密度,为Cr提供了大量短路扩散通道,降低了Cr选择氧化的临界浓度;基体表层Cr的短路扩散保证了Cr2O3膜稳定生长的扩散通量,从而抑制了Fe氧化物的形成.     

电弧离子镀NiCrAlY和NiCoCrAlYHfSi涂层抗高温氧化性能

采用电弧离子镀技术在镍基高温合金DZ22B表面包覆一层NiCrAlY和NiCoCrAlYHfSi涂层,对比了两种涂层的微观形貌、结构和抗高温氧化性能,并讨论了不同活性元素在氧化中的作用。结果表明:NiCrAlY涂层主要由γ′-Ni3Al/γ-Ni、β-NiAl和α-Cr相组成,而NiCoCrAlYHfSi除上述组成外还形成了NiCoCr合金相,两种涂层热处理期间均发生β-NiAl向γ′-Ni_3Al的转变过程。NiCrAlY和NiCoCrAlYHfSi涂层1 050℃恒温氧化200h的平均氧化速率分别为0.072 3g/(m~2·h)和0.052 7g/(m~2·h)。NiCrAlY氧化初期直接形成α-Al_2O_3、NiCr_2O_4和Cr_2O_3,随后出现裂纹、孔洞等缺陷,氧化物沿孔洞向涂层内部延伸,同时由于基材中的Ti元素发生外扩散,涂层中还形成了TiO_2。NiCoCrAlYHfSi氧化初期形成了亚稳态的θ-Al_2O_3,随后慢慢转变为α-Al_2O_3,氧化物层比NiCrAlY均匀致密,抗高温氧化性能更优异。     

添加Y对炮钢表面电弧离子镀(Ti,Al)N薄膜氧化性能的影响

利用电弧离子镀技术,在炮钢表面沉积TiAlN和TiAlYN两种薄膜,研究添加1%(原子分数)Y对(Ti,Al)N薄膜氧化性能的影响。两种沉积薄膜的样品在空气中850℃下氧化10h,用SEM、EDAX和XRD分别分析两种薄膜的形貌、成分及相组成。结果表明,在空气中850℃下氧化10h后,两种薄膜的氧化产物均为Al2O3和TiO2的混合氧化物;TiAlN薄膜的动力学曲线呈近似直线规律,而TiAlYN薄膜动力学曲线符合抛物线规律;前者表面氧化物晶粒粗大,而后者表面氧化物晶粒细小,且氧化膜厚度不足前者的一半;添加Y可以减少膜层表面液滴的数量,提高膜层的抗氧化性能。     

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.