氟化镧对多孔钛的影响研究

采用添加造孔剂法制备多孔钛,并且加入微量氟化镧以期得到高孔隙率高强度的多孔钛。选取三种不同粒径的钛粉做为原料,分别制备多孔钛,并且加入氟化镧探究其对多孔钛的影响效果。随着钛粉粒径的减小,多孔钛的开孔率、孔隙率随着下降,孔径尺寸略有减小;且多孔钛的抗压强度、弹性模量和抗弯强度随之增强,但不同粒径的多孔钛,氟化镧的增加效果不同,而细化晶粒是氟化镧能增强多孔钛力学性能的原因。综合考虑,C组(粒径最小)制备所得的多孔钛力学性能最佳,其中氟化镧的添加量为0.3%(质量分数)时抗压强度、弹性模量分别为157.84 MPa和3.73 GPa,抗弯强度为66.62 MPa。     

银含量对多孔钛微观结构和力学性能的影响

以具有抗菌性的银作为合金化元素,以碳酸氢铵作为造孔剂,应用粉末冶金的方法制备出不同银含量的多孔钛银合金,并应用称重法、带能谱的扫描电子显微镜、X射线衍射仪、万能力学试验机等研究了银含量对多孔钛微观结构和力学性能的影响。结果表明:银的添加量为3%时,多孔钛的孔隙率从65.18%升高到68.25%,多孔钛银合金的抗压强度和弹性模量均增加。进一步增加银的含量到10%时,多孔钛银合金的孔隙率保持在68%左右,其抗压强度和弹性模量变化较小。银的加入对多孔钛的孔结构无明显影响,其相成分主要为α-Ti。多孔钛银合金具有良好的孔结构和力学性能,有潜力用作抗菌骨科植入材料用于松质骨缺损修复。     

多孔Ti-5Ag合金的制备及力学性能研究

以钛粉和银粉为原料,不同含量的碳酸氢铵为占位剂,采用粉末冶金的方法制备多孔Ti-5Ag合金。结果表明制备的多孔Ti-5Ag合金的相组成为α-Ti。随着碳酸氢铵添加量的增加,多孔Ti-5Ag合金的密度逐渐降低,孔隙率逐渐增加。形貌观察表明随着孔隙率的增加,多孔Ti-5Ag合金中大孔的数量增多,并且孔与孔之间的连通性增加;力学测试显示其弹性模量和抗压强度均降低。多孔Ti-5Ag合金的力学性能可以通过控制碳酸氢铵的添加量调整到与人体骨匹配,有潜力作为多孔抗菌植入体用于骨科。     

钴对凝胶注模成形医用植入钛合金材料的影响

本文采用凝胶注模成形工艺,用钴包覆钛粉制备多孔钛合金植入材料。研究了钴对成形工艺中浆料的粘度、孔隙率以及烧结体的抗压强度的影响,预混液中有机单体的浓度、单体(AM)/交联剂(MBAM)的比例对坯体的强度的影响。通过改变烧结温度和固相含量,可以实现多孔钛钴合金的孔隙率和抗压强度分别在29%~58%、68~378 MPa范围内调节,采用含钴8%的钴包覆钛粉以33%的固相含量制备坯体,在1 130℃保温2 h制备的多孔钛合金材料,孔隙率为45.6%、抗压强度为227 MPa、抗弯强度为213 MPa、弹性模量为15.8 GPa,力学性能与自然骨接近,适宜做自然骨替代材料。     

模拟点蚀油气管线钢的拉伸性能

根据发生点腐蚀的油气管线基体有许多点蚀坑的特点,通过计算机产生随机数确定点蚀坑的位置,用小钻头打孔的方法模拟X60管线钢基体的多孔特征进行拉伸试验,测得其弹性模量、屈服强度和抗拉强度,并将理论计算值与前二者进行比较和修正,给出了多孔钢材的抗拉强度与孔隙率的函数关系.结果表明,多孔钢材弹性模量的实测值随孔隙率的变化与理论预测结果较为吻合;钢材实测屈服强度也随着孔隙率的增加而减少,但在较高孔隙率时其减少趋势变缓;衰减速率的实测值略大于理论预测值;实测抗拉强度随孔隙率的变化曲线与屈服强度相似,但对孔隙率更敏感.     

细长孔的多孔Ti-5Nb合金制备及力学性能研究

以钛粉和铌粉为原料,球形硬脂酸为占位剂,采用粉末冶金法制备出多孔Ti-5Nb合金,并用称重法、XRD、SEM和万能力学试验机等研究了硬脂酸添加量对多孔Ti-5Nb合金微观结构和力学性能的影响。结果表明:以球形硬脂酸为占位剂成功制备出了具有排列近似一致的、细长孔结构的多孔Ti-5Nb合金。当硬脂酸添加量从10%增加到50%时,多孔Ti-5Nb合金的相组成几乎没有变化,但其密度降低,孔隙率增大,大孔之间的连通性增加,弹性模量和抗压强度均降低。通过控制硬脂酸的添加量可以使多孔Ti-5Nb合金的力学性能与皮质骨和松质骨匹配。     

多孔TiNb合金的制备及力学与腐蚀性能研究

本实验采用粉末冶金法制备多孔Ti-35%Nb合金,并对其显微组织、力学及腐蚀性能进行了研究.所制备样品的孔洞分布均匀,孔的连通性好;显微组织主要由β-Ti组成,其压缩曲线表现出典型的开孔泡沫的特征;力学性能能够满足人体多孔骨的移植要求.随着孔隙率的增加弹性模量减小,但强度和腐蚀性能也同时下降.因此,对孔隙率的选择应综合这两方面来考虑.     

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。     

等离子喷涂 YSZ 可磨耗涂层孔隙率与力学性能关系研究

本文主要研究了多孔 YSZ 可磨耗封严涂层孔隙率与其力学性能的关系。 采用高能等离子喷涂制备了不同 孔隙率自支撑 YSZ 涂层试样, 采用三点弯曲实验研究了孔隙率与 YSZ 涂层室温和 1060 ℃高温力学性能的关系。 结果表明, 涂层孔隙率在 11.61%~28.80% 之间时, 室温下涂层断裂韧性为 12.48 MPa·m1/2~20.96 MPa·m1/2, 抗弯 强度为 17.10 MPa~43.75 MPa, 弹性模量为 3.64 GPa~13.13 GPa, 1060 ℃下涂层断裂韧性为 9.79 MPa·m1/2~13.71 MPa·m1/2, 抗弯强度为 20.20 MPa~35.12 MPa, 弹性模量为 5.15 GPa~11.00 GPa。 随孔隙率增加, 涂层断裂韧性增加, 抗弯强度、 弹性模量减小。 在中、 低孔隙率下, 涂层在高温下的抗弯强度、 弹性模量和断裂韧性低于室温, 在高 孔隙率下, 高温条件下涂层的抗弯强度、 弹性模量高于室温。 随着孔隙率的增加, 高温条件涂层力学性能的变化 趋势相较室温时更为平缓。     

造孔剂含量对粉末轧制制备多孔钛合金板的影响

采用体积分数为40%～70%的碳酸氢铵颗粒做造孔剂,通过粉末轧制技术成功制备了孔隙率为42.8%～68.5%的大尺寸多孔TC4钛合金板材。结果表明:当轧制工艺不变时,轧制压力和生板坯厚度随造孔剂含量的增加而降低。低温脱除造孔剂后高温高真空烧结制备所得的多孔钛合金板的孔隙率,随造孔剂含量的增加而增加,当造孔剂体积分数为60%～70%时,孔隙连接度增大,孔隙变均匀,孔隙率最高可达68.5%。当造孔剂体积分数由40%增加至70%时,多孔钛合金板的抗拉强度由124.7 MPa迅速降低至12.7 MPa;随着造孔剂含量的增加,多孔钛合金的受力由孔壁向孔棱过渡,断裂面不断减少。     

孔隙度对烧结不锈钢纤维多孔材料压缩性能的影响

采用丝径为100μm的不锈钢纤维经松装烧结工艺制备了孔隙度在70%～95%之间的金属纤维多孔板材.在MTS858材料试验机上检测压缩性能,结果表明:孔隙度在82.8%以下的试件的面内应力应变曲线大致分为三个阶段,应变很低情况下的线性弹性区、屈服平台区和应力急剧增大情况下的致密化区,其中屈服平台区较长,说明该材料具有较强的能量吸收能力;随着孔隙度的增加,不锈钢纤维多孔材料的卸载模量、屈服强度减小,其中孔隙度为70%的烧结不锈钢纤维多孔材料的平均卸载模量为5.2GPa,平均屈服强度达到了23MPa;孔隙度大于90.1%的试件屈服强度很低,能量吸收能力很小.     

Conventional Powder Metallurgy Process and Characterization of Porous Titanium for Biomedical Applications

Commercially pure titanium (c.p. Ti) is one of the best metallic biomaterials for bone tissue replacement. However, one of its main drawbacks, which compromises the service reliability of the implants, is the stress-shielding phenomenon (Young’s modulus mismatch with respect to that one of the bone). Several previous works attempted to solve this problem. One alternative to solve that problem has been the development of biocomposites implants and, more recently, the fabrication of titanium porous implants. In this work, porous samples of c.p. Ti grade 4 were obtained using conventional powder metallurgy technique. The influence of the processing parameters (compacting pressure and sintering temperature) on the microstructure features (size, type, morphology, and percentage of porosity), as well as on the mechanical properties (compressive yield strength, and conventional and dynamic Young’s modulus) were investigated. The results indicated that there is an increment in density, roundness of pores, and mean free path between them as compacting pressure and/or sintering temperature is increased. The Young’s modulus (conventional and dynamic) and yield strength showed the same behavior. Better stiffness results, in the central part of cylindrical samples, were obtained for a uniaxial compression of 38.5 MPa using a sintering temperature of 1273 K and 1373 K (1000 °C and 1100 °C). An evaluation of porosity and Young’s modulus along a cylindrical sample divided in three parts showed that is possible to obtain a titanium sample with graded porosity that could be used to design implants. This approach opens a new alternative to solve the bone resorption problems associated with the stress-shielding phenomenon.     

造孔剂法制备泡沫钛的研究现状与进展

泡沫钛融合了泡沫结构与金属钛的双重属性，具有出色的力学性能、优异的耐腐蚀性和良好的生物相容性等优点，在航空、航天、海洋工程、生物医学、能源与环保等领域应用前景广阔。基于粉末冶金技术的造孔剂法是目前制备泡沫钛的主流方法，不仅具有操作简单、设备要求低的优点，而且能通过调整造孔剂参数来控制最终制品的结构与性能。本文综述了造孔剂法制备泡沫钛领域的研究现状与进展，通过分析文献、整理数据，讨论了高孔隙率泡沫钛的研究历程和瓶颈问题，指出了泡沫钛孔隙率研究的发展趋势。     

Electrochemical Corrosion and Impedance Studies of Porous Ti–xNb–Ag Alloy in Physiological Solution

Porous titanium (Ti) and its alloys are promising materials for orthopedic applications due to their low elastic modulus, high strength, excellent corrosion resistance, and biocompatibility. In this study, the porous Ti–xNb–5Ag (x = 25, 30 and 35 wt%) alloys were synthesized using the powder metallurgy approach. The effects of Nb content on the porosity, mechanical properties, and electrochemical corrosion behavior of the alloys were investigated. XRD analysis revealed that the porous alloys mainly consist of α-Ti, β-Ti, intermetallic compound (Ti₄Nb), and oxides of TiO₂ and NbO phases. Porous alloys possess the porosity ranging from 57 to 65%, due to the addition of NH₄HCO₃ (45 wt%). Increase in Nb content lead to a reduction in the elastic modulus and compression strengths of the sintered porous Ti–xNb–5Ag alloys. All three developed porous Ti–xNb–5Ag alloys show the optimum combination of elastic modulus and compression strength, which is suitable for orthopedic applications. These porous alloys exhibit excellent electrochemical corrosion resistance in the simulated body fluids, and the samples having low porosity exhibit higher corrosion resistance than high-porosity samples.

     

Study of a 44NKhMT precision powder alloy produced from nanopowders

Properties of elinvars produced by a powder technology are studied experimentally at all hierarchic structural levels. The problems of an increase in the homogeneity of the structure and a decrease in the porosity of a powder elinvar are solved by alloying with titanium hydride and 2 wt % nickel powder with a particle size of 50–70 nm. A heat treatment regime is optimized to improve the mechanical properties, namely, the hardness, strength, modulus of elasticity, and porosity. Based on the studied laws of structure formation, a powder elinvar with properties similar to the corresponding cast alloy is produced: its density is 98%, the modulus of elasticity is up to 190 GPa, the ultimate strength is 1100 MPa, and the relative elongation is up to 13%.     

Processing and Pore Growth Mechanisms in Aluminum Gasarites Produced by Thermal Decomposition

Gasarites are a subclass of metallic foams that have a cylindrical pore morphology created by directional solidification of metals saturated with a gas. Thermal decomposition is an alternative process in which the soluble gas is delivered by decomposition of a particulate gas source. Aluminum gasarites formed through decomposition of titanium and zirconium hydrides were studied to both replicate the results of a previous study and discern pore-formation mechanisms. Replication of the previous study was not achieved, and additional processing enhancements were required to produce gasarite pore morphologies. For the first time, zirconium hydride was utilized to produce gasarites, with porosity levels and pore sizes lower than that from titanium hydride. Maximum average porosity levels of 10 and 6 pct were observed for titanium hydride and zirconium hydride, respectively. Pore-formation mechanisms in aluminum gasarite foams created via thermal decomposition of titanium and zirconium hydrides were evaluated through metallographic analysis and scanning electron microscopy. Definitive evidence of gas–metal eutectic pore growth was not found, but pore morphological characteristics and chemical analysis of particulate at pore surfaces support direct gas evolution from the hydride particles as a contributor to pore formation and growth.     

Porous titanium processed by powder injection moulding of titanium hydride and space holders

Abstract

Biocompatibility, bone-like mechanical properties, and good bone-to-implant anchorage are current requirements for permanent implants. Porous titanium can satisfy these requirements provided that sufficient porosity, large enough pores and interconnections allowing bone ingrowth can reliably be obtained with controlled processes. In the present work, porous parts are processed from titanium hydride based feedstocks containing space holders. Two formulations have been developed: a feedstock with a polyethyleneglycol based binder and NaCl space holders, and a feedstock with a paraffin based binder and PMMA space holders. Depending on the sintering conditions, porosity levels between 30 and 60% and open porosity between 10 and 40% are obtained, with pore sizes in the range 50–500 μm. The microstructure, porosity and mechanical properties of porous titanium sintered at various temperatures have been characterised by scanning electron microscopy and compression tests.     

蒙乃尔多孔板的力学性能研究

多孔板是流化床布气元件的关键部件。工作中受流动气体和物料的作用,在多孔板上产生一定的压力、拉力和剪切力,因此要求多孔板具有优良的力学性能。采用粉末冶金法制备蒙乃尔多孔板,测定其不同部位的压缩和剪切性能。结果表明:多孔板边部压缩屈服强度可达143 MPa,弹性模量可达18.1 GPa;中心部位压缩屈服强度可达67 MPa,弹性模量可达8.2 GPa;弹性应变区间可达到3.0%;边部剪切强度可达153 MPa,中心为87 MPa。     

轧钢铁皮制备多孔不锈钢化学成分及孔隙控制

 为了充分发挥氧化铁皮含铁品位高、杂质元素含量低、产生量大的优势和特点,并开发高附加值的金属制品,采用真空还原烧结的方法制备了316多孔不锈钢,并确定了适宜的制备工艺以及孔隙率的影响因素。研究过程中采用高温真空管式炉对试样进行还原烧结制备;采用直读光谱、氧氢氮联合检测仪、X射线衍射分析仪、扫描电镜等设备对试样的化学成分、物相组成和微观形貌进行了分析。研究结果表明,以轧钢铁皮为主要原料,配入还原剂及其他合金粉末,通过高温真空还原可以得到成分合格的316多孔不锈钢,确定最佳制备工艺为10-3Pa真空度、1 200 ℃下保温3 h;还原烧结过程中,锰合金的收得率仅为61%。制备出的试样为单一的奥氏体组织,同时有Cr₇C₃在晶内析出,晶界附近存在σ相析出。保温0~3 h内,试样的孔隙率由37.26%增加至40.27%,延长保温时间至4 h,金属颗粒之间的烧结更加完全,孔隙率降低至35.16%;将制坯压力由76.43增加至152.87 MPa,多孔不锈钢的孔隙率由42.07%降低至34.44%,呈现逐渐降低趋势。当制样压力大于152.87 MPa时,发生了造孔剂偏聚的现象,导致孔隙率略微增加至35.76%。造孔剂碳酸氢铵每多增加10%,多孔不锈钢的孔隙率增加9.3%。通过对正交试验分析发现造孔剂加入量对多孔不锈钢孔隙率的影响最为显著,制样压力次之,保温时间对孔隙率的影响最小。     

多孔碳化硼的力学性能及其微观组织

采用无压烧结法制备得到了多孔的碳化硼,用扫描电镜研究了该材料的微观组织;并测定了不同孔隙率碳化硼的抗弯强度和密度,分析了多孔碳化硼的孔隙率与抗弯强度和密度的关系。研究结果表明:采用无压真空烧结法所制备的多孔碳化硼材料的微观组织烧结良好,烧结颈明显,孔隙大小比较均匀;当空隙率为30%时,所制备的多孔碳化硼密度为1.714 g/cm3,抗弯强度为100.85 MPa。