铜合金表面新型金属陶瓷涂层材料的性能

航天发动机某热端零部件采用的QCr0.8材料,由于经受高温、高速富氧燃气的冲刷,通常会发生高温氧化或者冲刷烧蚀而失效,其应用条件严苛。经分析与研究,选择在Ni-Pb_3O_4-B_2O-BaO-SiO_2体系玻璃相中加入适当的磨料,成功地制备了铜合金表面新型金属陶瓷涂层。采用热震试验及氧化试验对比了磨料中不同比例的镍粉添加量对涂层性能的影响;根据宏观形貌观察并结合SEM微观形貌分析了涂层的形貌以及界面特点。结果表明:镍粉与玻璃熔块添加比为1.2∶1.0的涂料抗热震、抗氧化性能最好,可以有效保护基体。     

燃气发生器条件下穿刺C/C复合材料喷管的烧蚀性能研究

研究了穿刺C/C复合材料喷管在酒精/氧气燃气发生器模拟的液体火箭发动机富氧燃气环境中的烧蚀性能, 分析了穿刺C/C复合材料的烧蚀机理及燃气参数对烧蚀性能的影响. 结果表明, 喷管喉部线烧蚀率为(0.055±0.029)mm/s, 质量烧蚀率为0.186kg/(m²·s). 喷管收敛段下游到喉部区域烧蚀最严重, 收敛段上游其次, 扩散段烧蚀最弱. 烧蚀过程是热化学烧蚀和气流冲刷综合作用的结果, 燃气温度和氧化性组分H₂O和CO₂含量决定穿刺C/C复合材料热化学烧蚀率, 压强和流速影响穿刺C/C复合材料的机械剥蚀.     

3D C/SiC复合材料喷管在小型固体火箭发动机中的烧蚀规律研究

采用小型固体火箭发动机研究了3D C/SiC复合材料喷管的烧蚀性能,分析了3D C/SiC的烧蚀机理及燃气参数对烧蚀性能的影响.结果表明,喷管喉部线烧蚀率为0.128±40.088mm/s,质量烧蚀率为0.166kg/(m2.s);受喷管内燃气组分、温度、压强和流速等环境参数的影响,3D C/SiC的烧蚀涉及不同机理的非均匀烧蚀.喉部及其上下游过渡区域烧蚀最严重,收敛段其次,扩散段烧蚀最弱.烧蚀过程是热物理化学侵蚀和机械剥蚀综合作用的结果:涉及SiC的分解流失,SiC和碳纤维的氧化烧蚀,还涉及低速Al2O3大粒子的机械化学侵蚀,高速Al2O3小粒子的机械侵蚀等.     

碳/碳-碳化硅复合材料制备及性能研究

为了提高航母舰载机燃气导流板的性能, 对碳/碳-碳化硅 (C/C-SiC) 复合材料开展制备和性能研究。采用轴棒法编制预制体, 采用化学气相渗透工艺制备试件。将试件在舰载机的尾流中做模拟起飞工况的飞行试验。采用电子天平和千分尺测量试件的烧蚀率, 采用能谱分析测量燃烧产物的成份, 采用扫描电镜观察试件烧蚀后的微观形貌的变化, 并对试件的烧蚀机理进行分析。结果表明:试件的质量烧蚀率为0.0405 g/s, 线烧蚀率为0.0488 mm/s;试件中SiC在高温下反应生成的SiO₂在碳纤维的周围沉积, 形成了包鞘结构, 有效地阻滞了氧化反应向内部继续传递, 从而降低了试件的烧蚀率, 材料总体表现出优异的抗烧蚀性能。     

烧蚀时间对C/C-SiC复合材料高超声速富氧环境烧蚀机制的影响

为了研究烧蚀时间对C/C-SiC复合材料在高超声速富氧环境下烧蚀机制的影响规律,采用富氧环境下的高超声速烧蚀试验技术,对“化学气相渗透+先驱体浸渍裂解”混合工艺制备的针刺C/C-SiC复合材料动态烧蚀机制进行研究,并采用电子扫描显微镜观察烧蚀表面形貌。研究表明:在极端苛刻的高超声速富氧烧蚀环境下,C/C-SiC复合材料能够短时抵抗高温、高压、高超声速燃气射流的氧化工作环境。材料经高超声速富氧烧蚀10 s、20 s、30 s、40 s及50 s后的质量烧蚀率分别为0.021 g/s、0.025 g/s、0.027 g/s、0.026 g/s与0.034 g/s。C/C-SiC复合材料在高超声速富氧环境下的动态烧蚀行为主要受热化学烧蚀与机械剥蚀两种烧蚀机制共同作用。在初始阶段,SiO₂保护膜的存在有效阻止了氧化性组分向基体内部的扩散,仅材料中心区域存在轻微热化学烧蚀;烧蚀试验中期,材料的烧蚀主要表现为热化学烧蚀与机械剥蚀联合作用,并由热化学烧蚀向机械剥蚀呈渐变性转变;烧蚀试验后期,基体的深度反应使得材料的烧蚀主要表现为纤维与基体的大面积片状剥落。      

高速飞行器瞬态气动热试验模拟系统

为得到高速飞行器表面各部分的热应力，应变，结构膨胀量等高温力学性能参数，须建立高速飞行器瞬态气动热试验模拟系统。针对高速飞行器气动模拟试验瞬态热控过程所具有变化复杂，高度非线性，瞬变，强耦合的特点，将模拟控制方法应用于瞬态气动热模拟控制系统。该系统能够按照高速飞行器飞行过程中表面热流和温度的瞬态连续变化对气动模拟加热过程实施快速，准确的动态控制。     

高温烧蚀条件下 C/C材料热力耦合场模拟

热防护材料在高温、高焓、高压环境中因物理、化学和力学因素造成质量损失引起材料烧蚀,使其热力学和热物理性质发生不可逆变化, 表现出复杂的非线性特征。通过对碳基复合材料热化学烧蚀机理分析, 由质量守恒、能量守恒及系统化学反应的热化学平衡原理, 建立相应的热化学和热力学烧蚀模型。基于材料线烧蚀引起边界移动建立热传导方程; 对温度场以及热应力场求解时充分考虑材料变物性特征。通过数值模拟表征材料在高温烧蚀条件下的动态热力学行为, 与实验结果吻合较好, 实现了材料在高温、高过载等复杂因素耦合作用下的实时仿真。      

地面模拟再入烧蚀系统研究

为了模拟再入飞行的热环境,研制了基于热等离子体为热源的再入飞行地面模拟烧蚀试验系统.该试验系统将氩气和氢气等工作气体电离、加速后产生高温、高速的热等离子体射流,基于热量和Ma数等效来模拟再入飞行的热环境;根据能量平衡原理,给出试验系统的焓值、出口温度和速度等参数的计算方法,通过测量系统的输入电压、电流、水温、主气和次气的流量等,计算出一定工况下的参数分布;通过仿真计算,得出了系统的流场分布;并通过试验对计算结果进行了验证.该试验系统具有参数调节性好、精度高、应用范围广、可以模拟不同的再入飞行环境等特点,为再入热防护研究等方面提供了切实可行的试验手段.     

固液火箭发动机钨渗铜喉衬的烧蚀形貌及性能研究

以固体和液体混合燃料作为推进动力的固液火箭发动机具有特殊的高温、高压、氧化、粒子冲刷的燃烧环境。钨渗铜是一种自发汗冷却型高温材料,常用于发动机喷管的耐烧蚀部件。采用高温烧结-熔渗法制成钨渗铜合金喉衬,通过固液火箭发动机地面热试车考核,结果表明,钨渗铜喉衬在固液火箭发动机中最大平均线烧蚀率为0.151 mm/s。喉衬不同部位的形貌与烧蚀环境有关:收敛部分大量燃气组分以颗粒形态附着并形成层状结构;喉部区域包含燃气组分颗粒堆积和钨渗铜基体裸露两种形态;扩张部分形成均匀的烧蚀表面。收敛部分检出大量燃料元素(Al、Mg);喉部存在W和Cu的区域,其它区域为燃料粒子沉积;扩张部分存在大量背衬材料中引入的Si。     

有机无机转化法制备超高温陶瓷基复合材料技术研究

超高温陶瓷基复合材料是以连续碳纤维为增强体、超高温陶瓷为基体的一类复合材料,具有密度低、韧性好、耐高温、抗氧化及耐烧蚀等优异性能,在新型高速飞行器热结构应用方面有着不可替代的作用。碳纤维增强体和陶瓷基体是超高温陶瓷基复合材料的两个重要组成部分,对复合材料使役性能起着决定性作用,但是,碳纤维与陶瓷基体的理化性质差异大,如何将碳纤维与陶瓷基体进行有效复合,以便充分发挥碳纤维轻质、高强韧特性与陶瓷基体抗氧化、耐烧蚀特性,是超高温陶瓷基复合材料基础研究和工程应用需要解决的主要问题。本文论述了有机无机转化法制备超高温陶瓷基复合材料技术的发展思路,介绍了超高温有机陶瓷前驱体的设计与合成、C/ZrC-SiC和C/HfTaC-ZrC-SiC复合材料的研究结果,探讨了解决新型高速飞行器高温气动/燃气环境氧化烧蚀问题的材料技术方案,为连续纤维增强超高温陶瓷基复合材料的技术发展和工程应用提供借鉴。     

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.     

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.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to