Ti-Mo-Sn形状记忆合金管在微导尿管上的应用

Recently, minimally invasive surgeries using guide-wire, catheter, stent etc. have spread rapidly as the diagnosis and the medical treatment for a cancer, a disease in a circulatory organ etc. Currently, further maneuverability and functionability of those devices are strongly desired in order to be used widely and safely. Although Ti-Ni shape memory alloys have been used in medical devices such orthodontic wire, guide-wire, it has been suspected that Ni is allergenic and carcinogenic to the human body. Thus the development of Ni-free shape memory alloys has been strongly required. Re- cently, several Ni-free beta-titanium alloys such as Ti-Mo-Al, Ti-Mo-Ga, Ti-Nb-Al have been developed as new-type shape memory alloys. We have been studying Ti-Mo based beta-titanium alloys and Ti-Mo-Sn alloy has constantly superelasticity of 3%. The purpose of present study is to propose the micro catheter with thin wall and high flexibility using To-Mo-Sn alloys tube on the basis of its mechanical properties.     

An Evaluation of the Machinability of Nitinol SMA Using Combined Process of EP and MR Polishing

Nitinol,a shape memory alloy(SMA),is manufactured from titanium and nickel.It is employed in various fields for use in devices such as micro sensors,ultra-precision devices and satellite wings.It is highly recommended as a material in medical stents for insertion into the body because it has excellent organic compatibility.However,because they are intended to be inserted into the human body,products such as medical stents require a high-quality surface.Because nitinol has more of the characteristics of titanium than of nickel,one of its drawbacks is that heat generated in nitinol during machining is not discharged smoothly,leading to areas of inner stress which occur when traditional machining methods are used.To overcome this difficulty,various non-traditional machining methods,including non-contact machining,have been investigated for use with nitinol.This study is focused on the application of an effective fabrication method that combines electrolytic polishing(EP)and MR polishing to improve the surface integrity of nitinol through a series of experiments.Surface roughness variations of the polished nitinol were investigated by changing the imposed polishing conditions of EP and MR polishing,respectively.Finally,the variations in the surface roughness were observed with polished previously performed via the EP process.     

Corex-3000 taphole maintenance technology and practice

Short taphole length is one of the most troublesome problems of Baosteel's Corex - 3000 after its startup.Owing to the melter gasifier process,the char bed floated up and down as the level of hot metal and slag in hearth changing.These cause a lot of problems such as the heavy erosion of taphole areas and hard cast house work.The high second tapping flow is a noticeable characteristic of Corex process.The reasons of short taphole is analysed,and countermeasures are put into practice,some improvements are...     

Numerical simulation of tube profile growth during spray forming process

Spray forming is a new type of metal material forming process,which can produce metal blanks such as billet,tube,plate etc.A mathematical model has been developed to forecast the shape evolution of tube billets during the spray forming process.The atomizer mass flux as,radial distribution coefficient bs,draw velocity and diameter of mandrel were considered in this model and the influence of different parameters such as metal flowrate,draw velocity of mandrel,diameter of mandrel on the tube’s shape change were simulated and analyzed in this paper.The simulation results obtained from this model can be provided to engineers as reference.     

用电子束辐照法在模具表面制备陶瓷/金属复合层

Surface modifications,which result in formation of a hard layer such as CrN,TiN,TiCN etc. on tool surfaces,have been widely utilized in machining tools. How ever,the hard layer has clear interface with the matrix,thereby the delamination between the hard layer and matrix often occurs because of a mismatch of the thermal expansion coefficients. A composite layer with complicated interfaces between hard material and matrix is desired to avoid such a delamination due to a complicated interface existed between workpiece and coating materials. In this study,the formation of ceramic- metal composite layers on the surfaces of die steels by an electron beam( EB) irradiation technique has been investigated. When WC- Co powder was embrocated onto the substrate surfaces,a composite layer of WC- Co and matrix was formed through solidification after the irradiation-induced melting. The composite layer shows a marble- like texture with WC- rich regions. The hardness of the layer reaches up to 1000 HV. For other ceramic pow ders such as TiN and SiC,only small amount of particles has been incorporated into the composite layer,resulting in a relatively low hardness enhancement after the EB irradiation.     

Quantitative Study on Nonmetallic Inclusion Particles in Steels by Automatic Image Analysis With Extreme Values Method

 The presence of nonmetallic inclusion particles which appear during steelmaking process is harmful to the properties of steels, which is mainly as a function of some aspects such as size, volume fraction, shape, and distribution of these particles. The automatic image analysis technique is one of the most important tools for the quantitative determination of these parameters. The classical Student approach and the Extreme Values Method (EVM) were used for the inclusion size and shape determination and the evaluation of distance between the inclusion particles. The results thus obtained indicated that there were significant differences in the characteristics of the inclusion particles in the analyzed products. Both methods achieved results with some differences, indicating that EVM could be used as a faster and more reliable statistical methodology.     

Intracellular behaviour of samarium and europium in lactating mammary gland

The subcellular localization of samarium and europium, two rare-earths, increasingly used in both medical and industrial fields, has been studied in several organs such as liver and kidney but never in the mammary gland despite of its importance in the biology of lactation and nutrition domains. The intracellular behaviour of samarium and europium after their intra-peritoneal administration in the lactating mammary gland cells was investigated. The results showed the presence of very electron dense deposits in the glandular epithelial cell lysosomes. These particular lysosomes were never observed in the mammary cell lysosomes of control rats. These intralysosomal deposits were probably composed of insoluble samarium or europium phosphates by analogy with previous studies, the transmission electron microscopy, the ion mass microscopy and the electron probe microanalysis, and other techniques allowing the identification of the chemical structure of the intralysosomal deposits.     

Research on the Effect of Initial Crown on Hot Rolled Strip Shape

 Based on influence coefficient method, using the software of roll elastic deformation simulation, the effect of entry crown on hot rolled strip shape was researched and analyzed. According to the real condition of certain domestic hot rolled strip factory, the unit crown change from the first stand to the last was calculated when entry crown of hot strip alters. The calculation result shows that the entry crown effect not obviously on the target strip crown at the exit of last stand with the strip shape control reference such as bending force keeping fixed. The reason of calculation was analyzed, the research work refers theory support to strip shape setup modeling and shape control.     

Quantitative Evaluation Method of Shape Indicator for Cold-rolled Strip

Quantitative level evaluation of cold-rolled strip was significant for the shape control and the product structure optimization. Based on the probability statistics method and the shape pattern recognition method, the shape evaluation model of cold-rolled strip was established to evaluate real-time shape of the online strip. The model was embedded in the shape control system, and the online strip shape state was real-time observed whether to meet the technical indicators, so the shape level could be identified and evaluated. Based on the shape evaluation indicators, the shape component could be well controlled to improve the shape hit rate and the control stability, so that the rolled strip shape could meet the technical requirements. At a 1050 cold strip mill, the shape data of the scene typical specifications strip were online collected and real-time evaluated, and the hit of macro shape in less than 8 I was 68.44%, indicating that the mill shape control had considerable room for improvement, as well as the evaluation method was feasible and practical for quantitative evaluation of the strip shape. So the new evaluation model has important guiding significance to increase value-added and reduce product quality objection.     

Effect of Cooling Rate on Microstructure and Mechanical Properties of K465 Superalloy

 K465 superalloy, as a material for production of turbine nozzle, shows high mechanical properties as well as microstructure stability in critical and severe service conditions. The alloy gains its appropriate microstructure and strength through solid solution strengthening mechanism. Heat treatment parameters such as: time and temperature of homogenization, partial solution and aging temperatures, and cooling rate from solid solution affect the microstructure of the alloy. Among these parameters cooling rate from solid solution is the most effective. Therefore, in this study the effect of cooling rate on microstructure and mechanical properties (tensile and stress properties) were investigated. For this purpose, three different cooling rates were applied on the cast K465 specimens after solution treatment at 1210℃ for 4 h. Microstructures of the specimens then were studied using optical and electron microscopy. Also, tensile tests were performed at room temperature and stress rupture tests were performed under the condition of 975℃ and 230 MPa. It was found out that with increasing cooling rate the size of the γ' precipitates decreases and the mechanical properties of specimens increases. Also, it was shown that the shape and volume fraction of primary γ' particles are largely influenced by the cooling rate following solution treatment at 1210℃ for 4 h.     

金属硫化矿尘爆炸反应过程机理分析

金属硫化矿山存在粉尘爆炸的危险, 而爆炸反应过程机理尚需明确。通过热重分析试验, 了解金属硫化矿尘热反应过程;通过Factsage软件数值模拟, 半定量计算了热解产物, 验证了金属硫化矿尘热重分析结果的准确性;通过X射线粉末衍射仪表征, 分析了金属硫化矿尘在20 L球形爆炸容器中反应前后的物相。基于上述热重分析结果、物相分析结果, 及颗粒的气相、表面非均相燃烧理论, 重点建立了缩核—挥发分（shrinking core-diffusion limited volatiles explosion model, 简称SC-DLVC model）爆炸反应过程机理模型。归纳了当前粉尘爆炸动力学控制方程式及理论模型, 得到适用于金属硫化矿尘爆炸反应过程机理模型的方程式, 并提出今后修正方向。研究结果可为研究金属硫化矿尘爆炸的计算流体力学提供理论依据, 也可为预防金属硫化矿山粉尘爆炸提供理论支撑。      

The effect of aging temperature on transformation parameters of porous NiTi shape memory alloy fabricated by SHS

This study reports some different and efficient approaches for the aging temperatures which cause changes in the transformation parameters of porous NiTi (Ti-50.5 at % Ni) shape memory alloy (SMA) with porosity of 55.3% fabricated by self propagating high temperature synthesis (SHS). Changes which occurred in phase transformations due to the effects of various thermal procedures have been investigated by using X-ray diffraction. The micro structure was investigated using a scattering electron microscope and a light optical microscope. The shape memory behavior and transformation temperatures were studied through the differential scanning calorimetry (DSC). During the compression tests, it was observed that the compressive strength of the specimens was higher than the compact human bone, and that it increased with increasing aging temperature.     

Ti-C-3Ni-Al体系热爆合成反应及产物形态的研究

采用SEM和EDS分析对Ti—C-3Ni—Al体系热爆合成反应进行了研究。结果表明，由Ni和Al的放热反应引发Ti和C的强放热反应，体系生成了TiC／Ni3Al复合产物。体系成分和热爆温度是影响反应及产物形态的主要因素。TiC含量愈高，反应愈剧烈，TiC颗粒粒度愈大，产物致密性则先降低后升高。热爆温度愈高，反应愈剧烈，产物致密性相对愈好；TiC颗粒粒度随温度的升高而增大，形状从近球形发育成多边形。     

NaCl造孔剂添加量对多孔NiTi合金孔结构和力学性能的影响

选用Na Cl作为造孔剂,采用压制+烧结法制备孔结构和弹性模量可控的多孔Ni Ti形状记忆合金,采用SEM,XRD和形状回复率检测等测试手段研究造孔剂添加量对Ni Ti形状记忆合金的孔结构和力学性能的影响。结果表明:随Na Cl添加量增加,多孔体孔隙率从39%上升到72%,孔径大于50μm的孔隙数量明显增加;多孔体主要由Ni Ti奥氏体相(B2)和马氏体相(B19′)组成,并存在少量Ni Ti2,Ni3Ti和Ni4Ti3等相;合金的弹性模量随造孔剂的添加从30%时的10.8 GPa下降到70%时的1.5 GPa;当添加量为50%时,多孔体孔隙分布均匀,大于50μm的孔隙占45%,弹性模量为4.8 GPa,形状回复率达到最高值83%,最适合多孔植入体的要求。     

Experimental study on bone formation induced by porous HA-beta-TCP bioceramics

Three types of HA-beta-TCP active bioceramics which have various porosity and porous diameters were implanted into femurs and muscles of dogs. Histological and biomechanical tests proved that the porous HA-beta-TCP could make the active stage of bone formation moved up in bones and induce new bone formation in muscles. The pores were easily filled with new bones in samples which had smaller porous diameter than samples having larger porous diameter. The final strength after accomplishment of repair process was closely related with porosity. In samples with lower porosity, the proportion of organic bone and the strength were also lower, but in samples with higher porosity the proportion of organic bone and the strength were also higher. Up to the fourth month postoperatively, the strength of HA-beta-TCP with proper porous diameter and porosity which had been implanted into bones was as high as that of organic bone.     

等离子喷涂准晶热障涂层研究

采用等离子喷涂法制备了AlCuCoSi准晶涂层,并对其进行了结合强度、抗热冲击性能及热扩散率的测试,通过金相显微镜、X射线衍射(XRD)、扫描电子显微镜(SEM)等方法研究了涂层截面的形貌和结构。结果表明,采用等离子喷涂可以得到具有十面体准晶相的AlCuCoSi准晶涂层,其结合强度可达30MPa;经过100次400℃至室温的水淬热冲击后,涂层未脱落,具有良好的抗热冲击性能;喷涂后没有杂相生成;在600℃时,涂层的热扩散系数仍很低,可以作为热障涂层使用。     

富氧对高炉送风管用浇注料的性能与结构的影响

在实验室条件下,分析了不同通氧速率对高炉送风管用浇注料的性能与结构的影响。研究结果表明:通氧速率增加,抗压强度有所提高;1 200℃烧后体积密度从2.73g/cm3降到2.66g/cm3,气孔率由17.59%增加到19.47%;由于气孔增加,导热加快,在风管内衬比较薄的情况下,容易导致风管管壳发红;采用涂覆涂料封闭气孔的方法可以降低浇注料的传热,使风管的表面温度处于安全范围内。     

Influence of La2O3 on preparation and performance of porous cordierite from rice husk

A porous cordierite was synthesized at 1350 ℃ using rice husk as silica source and pore forming agent, and La2O3 as fluxing agent. The crystal phases of the cordierite were analyzed by X-ray diffraction (XRD) and their microstructures were observed by scanning electronic microscopy (SEM). The flexural strength, porosity and thermal expansion coefficient of the porous cordierite samples were inves- tigated in detail. Results showed that when 5 wt.% La2O3 was added, the flexural strength, porosity and thermal...     

锰粉矿烧结配矿工艺及其对产物性能的影响

锰矿是冶炼锰系合金的重要工业原料,目前中国大部分锰铁粉矿均经烧结后入炉冶炼,并且采用的是单烧。为了研究不同锰粉矿掺烧工艺对锰烧结矿性能的影响,并因此得到熔炼性能较优的烧结矿,采用马弗炉烧结法,改变原料配比、碱度、w(Mn)/w(Fe) 等因素,对3种锰粉矿配矿烧结工艺进行初步研究。采用X射线衍射、光学显微镜以及强度、气孔率等分析测试手段,对焙烧产物的常温物理性能、矿物组成和微观结构等进行分析。结果表明,当前试验条件下,碱度为0.70时的配矿方案一和方案四得到的焙烧产物抗压强度大、微观结构清晰、各物相分布较为均匀、气孔率高,适宜矿热炉冶炼,因此拟将该方案作为较优的工艺条件进行烧结杯放大试验。     

爆炸喷涂Cr_3C_2-35NiCr涂层的组织及性能研究

采用爆炸喷涂技术(D-gun)制备Cr3C2-35NiCr涂层。采用扫描电子显微镜(SEM)、电子探针(EPMA)、X射线衍射仪(XRD)对涂层微观结构、成分和相组成进行了分析,此外采用光学显微镜、显微硬度仪、拉伸试验机、摩擦磨损试验机等设备分别对涂层的孔隙率、硬度、断裂韧度、结合强度、磨损性能和热震性能进行了测试分析。试验结果表明:爆炸喷涂制备的Cr3C2-35NiCr涂层孔隙率为0.52%,显微硬度为HV803,断裂韧度为4.55MPa?m0.5,结合强度大于87.5MPa;涂层磨损性能和热震性能的测试结果表明,Cr3C2-35NiCr涂层室温摩擦系数为0.6,经受750℃下50次热震(水冷试验)无剥落。