纳米晶W-Cu合金粉体的冷压成形研究

研究了纳米晶Ｗ－Ｃｕ微粉在模压及冷等静压工艺下成形特性的对比,试验证明６００ＭＰａ压力下,冷等静压工艺较模压工艺获得的坏体致密度高于１５％,但冷等静压工艺中的包套除气对坯体致密及性能有较大的影响。     

建筑保温材料燃烧性能检测技术探析

在我国工业化进程的不断发展下,资源紧缺现象变得尤为严重。为了将建筑行业的能源使用效率加以提升,加大材料的有效利用是关键所在。对建筑外墙保温材料的燃烧性能做好相应的分析,不但可以将保温材料的利用率加以提升,而且还能够在某种程度上控制好防火性能。对此,本文主要从保温材料发展方向上出发,尝试对燃烧性能检测技术进行分析,笔者依据多年经验,提出合理化建议,提供给相关人士,供以借鉴。     

燃烧热值测量结果异常分析与解决方法

随着燃烧热值在各个领域中的广泛应用,其指标作用日趋重要,然而其测量结果准确性不高,误差相对较大,从而对材料本身性质的定位产生了偏差,其势必影响其后期使用。笔者通过制样方法、仪器稳定性等方面进行研究,对误差结果进行了详细的分析并提出了针对不同行业材料,引入特定测试方法,从而减少测量误差,为各个行业燃烧热值的测定提供参考。     

空化场中纳米镍磷合金粉体材料的制备

尝试利用自制的空化场电化学装置，在水溶液中制备纳米镍磷合金粉体材料，实验装置中包括以电火花技术为基础的空泡发生系统，反应容器，循环冷却系统，真空抽滤系统等。实验结果表明：在空化场的作用下，成功地在NiSO4和NaH2PO2反应溶液中制备出纳米尺度的镍磷合金粉体材料，该材料具有非晶态结构。材料的颗粒尺寸随空化场能量的提高而减小。典型的纳米镍合金的颗粒尺寸为80nm。     

铝热-离心法制备的铁镍基耐蚀合金的显微结构

研究了铝热-离心法制备的铁镍基合金内衬复合钢管的显微结构,分析了内衬层沿径向的成分分布。结果表明,铁镍合金内衬层与碳钢基体之间形成了一个宽约20μm的马氏体过渡区。内衬层合金元素的含量沿径向由内表面到外表面逐渐降低。铁镍合金铁素体区内有细小的AlNi₃和AlNi析出物。     

燃油燃烧器的雾化与燃烧仿真研究

以内回油机械雾化燃油燃烧器为例进行雾化与燃烧仿真研究,研究配风对雾化锥的影响。结果表明:喷油口孔径增大时,雾化锥角增大;喷油口孔长度减小,雾化锥角增大。直流风量增大时,雾化锥被拉长,火焰变得细长;直流风量减小,雾化锥的长度被缩短,火焰变得粗短。当配风使得过氧量在2%附近时,最高温度和平均温度的值取得最大,热效率最高,因此确定合理的配风是过氧量的2%～4%。     

Ce对铝青铜合金粉体材料涂层在5.0% H2SO4溶液中腐蚀行为的影响

利用等离子喷焊技术,将自主研究开发的多元铜合金粉末(含Ce和不含Ce)涂覆在45#钢表面,通过静态浸泡腐蚀实验、电化学实验,采用X射线衍射、表面EDS、EPMA等分析手段,研究Ce对多元铝青铜粉末熔覆层在5.0%H2SO4溶液中耐腐蚀性能及腐蚀行为的影响。结果表明,在5.0%H2SO4溶液中,合金粉体涂层发生了选择性脱成分腐蚀,稀土元素Ce能改善铝青铜合金粉体涂层的自腐蚀电位,提高该涂层的耐腐蚀性能。     

超细银钯合金粉的制备方法

采用液相法,把银钯离子还原成超细合金粉末.通过控制反应体系的PH值、浓度、温度及还原剂的种类和还原速度来控制合金粉的粒径大小及其分布.在一定温度下对粉末进行热处理,可减小粉末的表面积,有助于合金化程度的提高.利用本法制备的银钯合金粉具有粒度小、比表面积小、合金化程度高、重现性好等特点.适用于制造浪涌电阻浆料、大功率电阻浆料、片式电阻浆料及银钯导体浆料.     

试析天然气锅炉中的天然气燃烧及调整

天然气锅炉通常采用扩散与预混两种燃烧方式,本文针对天然气锅炉中的燃烧方式及其调整进行了较深入地分析,对于提高天然气锅炉燃烧效率具有十分重要的意义。     

典型硼化合物对毛竹热降解与燃烧性能的影响

利用热重和锥形量热仪研究硼酸、硼砂两种典型硼化合物对毛竹热降解和燃烧性能的影响。结果表明:硼酸、硼砂能降低竹材的最大热解速率,缩短高温热解区间,促进残炭生成。与未处理材相比,硼酸、硼砂明显减少竹材燃烧过程中的热量释放,热释放速率降至未处理材的50%左右,总热释放量的降幅分别达50.6%、44.1%。硼酸、硼砂也能抑制竹材燃烧时的烟释放,总烟释放量分别下降95.3%、91.6%。硼酸、硼砂处理竹材能发挥高效的阻燃抑烟功效。     

TiAl合金粉末热等静压组织及其力学性能均匀性研究

目的 研究圆柱包套经热等静压后内部不同位置粉末TiAl合金的组织与力学性能,为后续复杂结构包套热等静压整体成形工艺优化提供参考.方法 将装填有Ti-47Al-2Cr-2Nb雾化粉末的不锈钢包套在1230℃/170 MPa/3.5 h条件下热等静压,利用扫描电子显微镜观察烧结后包套内不同区域的显微组织,利用显微硬度计测量...     

机械合金化制备的Fe1-xNix合金纳米晶粉末的形貌和微结构

利用机械合金化方法制备了Ｆｅ１－ｘＮｉｘ合金纳米晶粉末,Ｘ分别为０．１５、０．４５、０．８０,球磨时间为２、４、８、１６、４０ｈ。利用扫描电子显微交易和坶分析仪观察和分析了样品的形貌和微结构。发现整个球磨过程枳发为３个阶段。开始阶段,由于冷焊,Ｆｅ、Ｎｉ混合粉末凝聚成一些粒径较大的颗粒;在中间阶段,内应力达到最大值,原先形成的大颗粒破碎,粒径分布变窄;最后阶段,ＦｅＮｉ粉完全合金化,粒度再次增大,     

电镀钨合金镀层组织及其耐腐蚀性能研究

主要分析了电镀钨合金镀层质量及其耐H2S-CO2腐蚀性能。通过SEM、EDX和XRD分析发现镀层与基体结合强度较高,但镀层淬火处理时出现龟裂现象,裂纹均匀排布于镀层表面。腐蚀评价表明腐蚀作用只发生在镀层淬火所形成的裂缝部位,造成裂缝内部充满大量腐蚀产物,非裂纹表面未见腐蚀。指出镀钨合金若用于酸性环境,尚需优化配方、降低硬度、增加韧性,此外还应检测基材屈服强度85%拉应力下的镀层应力腐蚀开裂行为。     

Combustion Synthesis: Effect of Urea on the Reaction and Characteristics of Ni-Zn Ferrite Powders

The purpose of this study was to evaluate the effect of the urea content (fuel) on the reaction and the characteristics of Ni-Zn ferrite powders obtained by combustion synthesis. Several batches were prepared with different fuel contents, ranging from the stoichiometric composition between 20 and 100% (excess), while the desired molar proportion of the metal precursors was kept constant. The solutions were heated on a hot plate and then transferred to a muffle furnace preheated to 700°C, in which ignition took place. The resulting powders were characterized by XRD, BET, SEM, and sedimentation, aided by rotation measured through an optic light. The crystalline hematite (-Fe₂O₃) and Ni-Zn ferrite phases were present in all the compositions studied, and the appearance of the agglomerates varied from soft to hard with increasing urea content. The increased urea content, which promoted a longer flame time, influenced the growth and/or formation of hard agglomerates. After sintering at 1200°C/2 h using the stoichiometric composition, only the spinel structure Ni-Zn ferrite, with homogeneous microstructure, was present.     

AZ31镁合金粉末氢气氛下机械球磨的组织演变

在氢气氛下机械球磨AZ31镁合金粉末,利用机械力作用使镁合金粉末与氢气发生反应生成纳米晶MgH2,用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等方法观察和分析了镁合金粉末与氢气在球磨过程中的微观组织演变.结果表明:球磨初始阶段粉末颗粒被碾压成扁平状,随着球磨的进行粉末颗粒逐渐细化,球磨至80h,形成粒度1～3μm、晶粒尺寸10nm左右的纳米晶MgH2粉末材料.     

Microstructure and Electrochemical Characteristics of Advanced Composite Zr-based Hydrogen Storage Alloy

Zr0.9Ti0.1(Ni,Co,Mn,V)(2.1) as-cast alloy was prepared by melting under Ar atmosphere; and then, four composite alloys were prepared by ball-milling after hydrogen absorbing agent was added. The initial discharge capacity was as high as 430 mAh .g(-1) for composite alloy electrode c discharged at 60 mA .g(-1) current density and its maximum capacity reached 505 mAh .g(-1). All composite alloy electrodes have good activation behavior, being fully activated in one or two cycles. At 300 mA .g(-1) current density, the composite alloy electrode c was found to have good cycle stability.     

Microstructure and Thermal Diffusivity of Ceramic Powders

For the first time, the thermal diffusivity (α) in red clay samples has been determined as a function of the annealing time, for a furnace temperature above 900°C. The thermal diffusivity measurements on the samples were obtained by means of the photoacoustic technique in a heat transmission configuration. A complementary microstructure analysis using X-ray diffraction (XRD) and energy dispersion spectroscopy (EDS) has been performed. The ceramic material used in this work is widely used in the fabrication of several kinds of building materials such as bricks and roof tiles in the north oriental region of Colombia (Cúcuta). The importance of these results is in the determination of conditions to obtain manufactured products with the desired heat transport capacity. Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

Microstructure and Wear Characteristics of Al-4.5Cu-5Pb Alloy

Al-4.5Cu-5Pb alloy was prepared by sand and chill casting. The same alloy was also spray deposited at a gas pressure of 1.6 MPa. The microstructural features exhibit a coarse to fine dendritic morphology for sand and chill cast alloys. Equiaxed grains were observed for spray fOrmed alloys. Wear testing employing a pin-on-disc type set-up, reveaIs considerably lower wear of spray deposited alloy compared to that of chill and sand cast alloys. The morphological features of wear track on specimen and debris indicated a mixed oxidative-cum-adhesive wear mechanisms for these alloys tested in the present investigation     

Microstructure and Magnetic Properties of Fe-Ni Alloy Fabricated by Selective Laser Melting Fe/Ni Mixed Powders

Fe—Ni alloy,as a widely applied ferromagnetic material,is synthesized using selective laser melting(SLM).The chemical compositions and microstructure of the SLM Fe—Ni alloy are characterized by X-ray diffraction(XRD), energy dispersive X-ray spectroscopy and scanning electron microscopy.It was found that the samples exhibited fine grains with homogenous distribution when a low laser scanning velocity was used.Moreover,the magnetic properties of the samples with different laser parameters are also measured.It shows that the SLM Fe—30%Ni alloy possesses a low coercivity and high saturation magnetization.It also can be obtained that SLM is an alternative faster method to prepare soft magnetic material with complex shapes.Moreover,the magnetic properties can be influenced by the laser parameters.