等离子喷涂Al2O3p/NiCrBSi涂层组织与性能

为了研究粉末结构对复合材料涂层组织与性能的影响规律,采用双路送粉方法、高能球磨团聚粉末及包覆混合粉末等离子喷涂制备Al₂O_3p/NiCrBSi 复合材料涂层.利用激光共聚焦扫描显微镜（LCSM）、扫描电子显微镜（SEM）、场发射扫描电子显微镜（FESEM）、x 射线衍射仪（XRD）及冲蚀磨损试验机等研究了涂层的微观组织和抗冲蚀磨损性能.结果表明,复合材料涂层主要由αAl₂O₃、γAl₂O₃、γNi、Ni₃B、CrB、Cr₂B、M₇C₃和M₇C₃相组成, Al₂O₃增强体颗粒分布于基体层片间或层片内.粉末结构对涂层的组织与性能具有明显的影响,采用包覆混合粉末制备的Al₂O_3p/NiCrBSi 复合材料涂层结构致密,具有更高的抗冲蚀磨损性能.     

喷涂工艺对陶瓷/金属自反应复合涂层组织的影响

用等离子喷涂的方法喷涂自制的Fe2O3 Al自反应复合粉,在金属表面制备了陶瓷-金属多相自反应复合涂层．研究了复合粉和涂层的微观结构,以及喷涂工艺参数对复合粉反应程度及涂层组织的影响．研究发现,喷涂距离是影响复合粉反应程度及涂层组织结构的主要因素,枪距在100mm时,反应最充分,涂层组织最致密．     

热喷涂HA复合涂层的组织分析

为了制备羟基磷灰石（HA）复合涂层,采用化学沉淀法制备羟基磷灰石粉末,对制备的超细粉末加入PVA溶液充分搅拌、干燥、研磨和过筛,制备出微米级、近似球状的、在等离子送粉器中容易流动的羟基磷灰石粉末.利用等离子喷涂和电弧喷涂的复合喷涂方法制备出羟基磷灰石不锈钢复合涂层和氧化铝不锈钢复合涂层,并通过扫描电镜分析了涂层的组织形态.结果表明,羟基磷灰石粉末比重很轻,不易进入等离子弧中心而被融化,等离子弧将羟基磷灰石粉末加热并载入电弧喷涂气流中,由不锈钢雾化液滴一并打在基体上形成复合涂层.对于氧化铝/不锈钢涂层和复合涂层,2种粒子虽然分布不均匀,但却获得了良好的冶金结合.     

激光熔覆钛基复合涂层的显微组织和硬度分析

采用激光熔覆快速非平衡合成方法制备了原位反应合成TiB增强钛基复合材料.用Y2O3、Ti和B的混合粉末在Ti-6Al-4V基体表面激光熔覆制得TiB/Ti复合涂层.采用X线衍射仪(XRD)、扫描电子显微镜(SEM)、能量散射光谱仪(EDS)和硬度测试等方法,研究了原位合成TiB/Ti复合涂层的显微结构和显微硬度.结果显示:激光熔覆层的相结构主要为α-Ti和TiB两相,TiB增强相均匀地分布于复合涂层中,熔覆层的硬度值高于基体Ti合金的硬度值1倍以上,Y2O3含量(质量分数w,全文同)为1％的激光熔覆涂层内部的增强相组织最为均匀、细小,且硬度值也最高,平均硬度(HV)值约为830.     

排塑工艺对钢水余热衬瓷技术的影响

针对表面涂层技术工艺复杂、高耗能、结合不牢固等缺点,利用钢水余热衬瓷技术制得了金属表面衬瓷层.该技术核心之一是配制合格的复合粉.在配制过程中加入了粘结剂(PVB),但使用之前需将其排出.把混合均匀的铁粉和铝粉以及纯PVB一起放在实验箱式炉中加热,确定出了排塑的最佳工艺.利用XRD分析了合金的氧化程度,用SEM比较了排塑完全和未排塑完全的衬瓷铸件的组织.结果发现430℃×1h为最佳排塑工艺;排塑完全的衬瓷铸件表面平整光滑、衬瓷层与基体结合强度高.     

Microwave sintering of W-15Cu ultrafine composite powder prepared by spray drying &; calcining-continuous reduction technology

The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying & calcining-continuous reduction technology were investigated.In comparison to the conventional H2 sintering processing,microwave sintering to W-15Cu can be achieved at lower sintering temperature and shorter sintering time.Furthermore,higher performances in microwave sintered compacts were obtained,but high microwave sintering temperature or long microwave sintering time could result in coarser microstructures.     

Effects of parameters on formation and microstructure of surface composite layer prepared by lost foam casting technique

Surface composite layer was fabricated on the AZ91D substrate using the lost foam casting (LFC) process. The pre-coating layer reacted with melt substrate and formed the composite layer, and the coating was mainly consist of alloying aluminum powder and low-temperature glass powder (PbO-ZnO-Na2O). The vacuum degree, pouring temperature, mold filling process of melt, and pre-coating thickness played an important role during the formation process of composite layer. The results show that surface morphology of composite layer can be divided into three categories: alloying effect of bad and good ceramic layer, alloying effect of good and bad ceramic layer, composite layer of good quality. The main reason for bad alloying layer is that alloying pre-coating thickness is so thin that it is scoured easily and involved in the melt, in addition, it is difficult for melt to infiltrate into the alloying coating owing to the surface tension of coating when the vacuum degree is excessively low. Bad ceramic layer is because of somewhat lower pouring temperature and the thicker alloying coating, due to the absorption of heat from the melt, making low temperature glass powder pre-coating layer fuse inadequate. Thus, to get good quality composite layer, the process conditions must be appropriate, the result shows that the optimum process parameters are as follows: at a pouring temperature of 800 ℃, vacuum degree of -0.06 MPa, alloying pre-coating thickness of 0.4 mm, and low glass powder pre-coating layer thickness of 1 mm.     

(Fe-Al)/Al_2O_3复合纳米粉体的机械球磨特性

采用机械球磨的方法制备(Fe Al)/Al2O3复合纳米粉体,通过对粉体的X衍射分析研究其机械球磨特性.结果表明:Al2O3阻碍球磨过程中的Fe、Al合金化,有利于粉末的纳米化和机械活化,并大幅提高出粉率.这对机械活化烧结FeAl基Al2O3弥散型块体复合纳米材料,提高机械球磨效率具有重要意义.     

Low-temperature sintering of FeCuCo based pre-alloyed powder for diamond bits

We studied the effects of sintering temperature on FeCuCo based pre-alloyed powder for diamond bits.The FeCuCo composite was fabricated by co-precipitation method.With the addition of tungsten carbide(WC),sintering under different temperatures was investigated.Mechanical properties of the FeCuCo based matrix were systematically studied.The structure of the composite was evaluated by X-ray diffraction(XRD) and scanning electron microscope(SEM) was used to analyze the surface of the powder and matrix.The suitable sintering temperature was determined through differential scanning calorimeter(DSC).Micro drilling experiments were performed,and 820 ℃ was identified to be the ideal sintering temperature,at which the matrix shows the best mechanical properties and drilling performance.     

TiO_2/ZnO超细粉体对PET纤维抗紫外性能及力学性能的影响

采用硅改性法对TiO2/ZnO复合粉体进行表面改性。通过在聚酯中添加改性TiO2/ZnO复合粉体形成共混体系,对TiO2/ZnO复合粉体的抗紫外性及其与聚酯共混纺丝后改性涤纶纤维的力学性能进行了研究。研究表明,经过表面改性后的改性剂最佳质量分数为0.1%,TiO2和ZnO粉体的添加量为1∶1时抗紫外线的效果最好,且粉体添加量越大,纤维的力学性能下降越多。     

粉末冶金法制备Al—12％CuO系原位铝基复合材料的组织和性能

为了制备组织均匀、压缩性能良好的原位纳米颗粒增强铝基复合材料,本文以微米级纯铝粉和氧化铜粉为原料,用改进的高能球磨＋粉末冶金技术制备了原位增强铝基复合材料,研究了所制备的铝基复合材料的显微组织和密度、压缩强度等性能与制备工艺的关系．研究发现：高能球磨480r／min,16h＋单向模压热压烧结620℃,100MPa,1h,获得纳米级CuAlO2原位增强的铝基复合材料,在铝基体中均匀分布大量尺寸约1μm的CuAl2相．热压工艺对所制备的铝基复合材料的压缩强度有显著影响,620℃,100MPa单向模压复合材料的压缩强度为843．6MPa,而双向加压材料的压缩强度提高到950MPa;当单向压力提高到150MPa时,原位铝基复合材料的压缩强度进一步提高到1090MPa．     

SELF-PROPAGATING HIGH-TEMPERATURE REDUCTIVE SYNTHESIS OF TiB_2 CERAMIC POWDER

SHS method with reductive process wasused to synthesize TiB_2 ceramic powder from B_2O_3-TiO_2-Mgsystem. X-ray diffraction, SEM and Image analysis wereused to analyse microstructure of TiB_2 powder and comparewith microstructure of TiB_2 fabricated by SHS elements syn-thesis from Ti B system. The results show that TiB_2 powderfabricated by SHS reductive synthesis is finer (about 1.5μm), uniformer and free-agglomerate.     

Electrical Breakdown Characteristic of Nanostructured W-Cu Contacts Materials

Nanostructured （ NS ）W-Cu composite powder was prepared by mechanical alloying （ MA ）, and nanostructared bulk of W-Cu contact material was fabricated by hot press sintering in an electrical vacuum furnace. The rnicrostructure, electric conductivity, hardness and break down voltage of NS W- Cu alloys were measured and compared to those of conventional W-Cu alloys prepared by powder metallurg＇y. The experimental results show that microstructural refinement and uniformity can improve the breakdown behavior and the electric arc stability of nanostructared W- Cu contacts materials. Also, the wanostructured W- Cu contact material shows the characteristic of spreading electric arcs, which is of benefit to electric arc erosion.     

Properties, phases and microstructure of microwave sintered W-20Cu composites from spray pyrolysiscontinuous reduction processed powders

The effects of microwave sintering on the properties, phases and microstructure of W-20Cu alloy, using composite powder fabricated by spray pyrolysis-continuous reduction technology, were investigated. Compared with the conventional hot-press sintering, microwave sintering to W-20Cu composites could be achieved with lower sintering temperature and shorter sintering time. Furthermore, microwave sintered W-Cu composites with high densification, homogenous microstructure and excellent properties were obtained. Microwave sintering could also result in finer microstructures.     

Hot compressive deformation behavior of an in-situ TiB whisker reinforced Ti matrix composite

An in-situ TiB whisker reinforced Ti matrix (TiBw/Ti) composite is fabricated by powder metallurgy technique followed by hot extrusion. Hot compressive deformation behavior of the composite, in which the TiB whiskers were oriented along the extruded direction, is investigated. The results indicate that the hot compressive resistance of the TiBw/Ti composite is higher than that of the unreinforeed Ti, and hot compressive resistance of the composite in the direction parallel to the whisker orientation is higher than that in the direction perpendicular to the whisker orientation. The hot compressive resistance of the composite increases with increasing strain rate and decreasing temperature. With increasing test temperature, the rate of the decrement of the compressive flow stress of the composite is higher than that of the unreinforced Ti. With increasing amount of compressive deformation, more and more TiB whiskers rotate and break during deformation. The rotation of the whiskers is easier at higher temperature, while, at lower temperature it becomes more difficult and whisker breakage becomes much more serious.     

高电位CuV_2O_6正极材料在热电池中的应用

采用固相法以CuO粉末和V2O5粉末为原料制备α-CuV2O6粉末,用X射线衍射分析(XRD)、差热分析(DTA)和粒度分析方法对铜钒氧材料进行了表征,并对其作为热电池正极材料的电化学行为进行了研究。电化学性能测试表明,制备的α-CuV2O6电极单体电池具有较高的放电电压和较大的放电比容量。     

湿化学法制备ATO/TiO2导电复合粉体包覆机制的研究

采用湿化学共沉淀法,通过在TiO2颗粒表面包覆Sb掺杂SnO2（ATO）制备ATO/TiO2导电粉.运用TG-DSC、XRD、XPS、SEM、BET和电导率等手段对ATO/TiO2导电粉进行了表征.研究结果表明：锡锑混合物xSn（Sb）O2·yH2O以非晶态的形态靠范德华力与静电引力吸附在TiO2表面,煅烧过程中,xSn（Sb）O2·yH2O脱去结晶水吸附或鍵合在TiO2表面.随着TiO2颗粒表面包覆层ATO厚度逐渐增加,ATO/TiO2粉体的电导率逐渐增加.     

锆瓷口腔修复材料用复合粉体的研制

采用不同粒度、纯度的原料 ,根据不同的配方 ,采用沉淀包裹法、共沉淀法和混合法等制粉方法制备出了锆瓷口腔修复材料用复合粉体 ,对不同方法制备的复合粉体性能进行了综合比较 .研究发现 :采用沉淀包裹可以制得 t- Zr O2 含量较高的复合粉体 ,采用沉淀包裹法制备的复合粉体比共沉淀和混合法综合效果好 .     

ON ZrO_2-NiCr COMPOSITE POWDER FOR SPRAYING

Composite powder prepared of calcium ox-ide stabilzed ZrO_2 (CSZ)and NiCr by vacuum sintering isstudied, and the effect of additive TiO_2,on its properties isdiscussed. The morphology and phases of the powder weremeasured and determined by SEM.EPMA. XRD methodsand the testing of flowability, bulk density and microhard-ness. The results show that the metallic camponents in thepowder are in homogeneous distribution,the flowability.bulkdensity and microhardness are superior to the ZrO_2-NiCrpowder prepared by mechanically mixing. All components inthe coating made of the composite powder are well-distribut-ed because of avoiding segregation in the middle of mixing.It proves that the comopsite powder is an excellent materialfor plasma spraying.     

BaZr0.9Y0.1O2.95/Na2SO4 composite with enhanced protonic conductivity

Heterogeneous composite BaZr_0.1Y_0.9O_2.95/Na₂SO₄ was designed and fabricated with Y-doped BaZrO₃ as matrix and Na₂SO₄ as dispersant by conventional powder processing to improve the total conductivity of barium zirconate. The electrical conduction of the composite was studied by electrical and electrochemical methods. Microstructure of the heterogeneous composite was examined by SEM. The experimewtal results show that the protonic conductivity of Y-doped BaZrO₃ is greatly improved upon incorporating Na₂SO₄ in the material. Microstructure observation indicates that a multiphase structure with Na₂SO₄ disperses at the grain boundaries of BaZr_0.1Y_0.9O_2.95. Electromotive force (EMF) measurements under fuel cell conditions reveal that the total ionic transport number of the composite is more than 0.9 at 750 °C. Funded by the National natural Science Foundation of China(No. 50872090)