不同制备工艺对Ti84Mo16合金弹性模量的影响

针对"硬组织置换"材料的低弹性模量要求,基于粉末冶金法,探索了不同制备工艺对Ti84Mo16合金弹性模量的影响规律。结果表明:当烧结温度高于1150℃时,烧结温度对Ti84Mo16合金弹性模量影响不是太大,但1050℃烧结的Ti84Mo16合金表现出很低的弹性模量;当球磨时间小于5h,球磨时间对Ti84Mo16合金弹性模量影响不是太大,但随球磨时间增加至10h,Ti84Mo16合金弹性模量下降;球磨粉体制备工艺和原子雾化粉体制备工艺对Ti84Mo16合金弹性模量影响差异不大;在合金粉中掺杂纳米纯钛粉体,可近似地看成是一种以Ti84Mo16合金为基的纯钛颗粒增强复合材料,其弹性模量随Ti含量增加而增加,弹性模量近似满足该复合材料的混合定律。     

纳米纯钛掺杂对Ti84Mo16合金多孔材料力学性能优化探索

针对医用ZhAO硬组织置换材料的低弹性模量要求,基于粉末冶金制备工艺,探索制备Ti84Mo16合金多孔材料,并以纳米纯钛粉体作为掺杂物,探索纯钛掺杂对Ti84Mo16合金多孔材料力学性能的优化作用。研究发现,在5 h球磨Ti84Mo16粉体中掺杂纳米纯钛粉体,经1200℃烧结工艺后制备的Ti84Mo16合金多孔材料力学性能得到优化,其强度和塑性都得到改善。     

孔隙率对Ti84Mo16合金多孔材料力学性能影响研究

基于粉末冶金制备工艺,以降低生物医用Ti84Mo16合金的弹性模量为目标,用碳酸氢氨作为介质掺杂粉体制备Ti84Mo16合金多孔材料。探讨不同孔隙率对Ti84Mo16合金多孔材料力学性能的影响规律。结果表明,孔隙率对Ti84Mo16合金多孔材料力学性能有着明显的影响,随着孔隙率增加,Ti84Mo16合金多孔材料力学强度呈几何指数下降,孔隙率对Ti84Mo16合金多孔材料力学性能影响规律满足Lorna J.Gibson及Michael F.Ashby的经典理论。同时2小时球磨Ti84Mo16合金多孔材料具有较高强度,5小时球磨Ti84Mo16合金多孔材料具有较好塑形。     

球磨时间对Ti_(84)Mo_(16)合金多孔材料力学性能的影响

基于粉末冶金制备工艺,采用碳酸氢氨介质法制备了不同孔隙率Ti84Mo16合金多孔材料。实验以球磨时间作为研究对象,探索球磨时间对Ti84Mo16合金多孔材料力学性能的影响规律。实验结果表明:球磨2 h可以得到强度较高的Ti84Mo16合金多孔材料,而球磨5 h可以得到塑性较高、力学综合性能较好的Ti84Mo16合金多孔材料,同时5 h及以上球磨时间是制备纯β相Ti84Mo16合金多孔材料的合适球磨时间。     

基于硬组织置换应用的Ti_(84)Mo_(16)合金研究进展

介绍了Ti84Mo16合金制备工艺及力学性能优化研究、Ti84Mo16合金表面活性化研究及羟基磷灰石活性涂层培养、Ti84Mo16合金多孔材料制备工艺及力学性能优化探索等方面的研究工作进展情况。Ti84Mo16合金近年来的研究成果为新一代生物医用钛合金开发领域进行了探索。     

医用钛钼合金粉末冶金制备工艺参数研究

研究了球磨时间和烧结温度对钛钼合金力学性能和弹性模量的影响.结果表明:粉末冶金工艺制备的钛钼合金具有良好的力学性能、较低的弹性模量和均匀的微孔结构,与"硬组织置换"材料要求性能所匹配;2h球磨适合制备强度较高的钛钼合金,5 h球磨则可以制备塑性良好、性能全面的钛钼合金;1200℃是钛钼合金较为理想的烧结温度;5 h球磨1150℃烧结就可以得到完全合金化的纯β相钛钼合金.     

微量合金元素Ti、Zr对Mo合金性能和显微组织的影响

采用粉末冶金法制备Mo-Zr、Mo-Ti合金,研究了Zr、Ti的添加方式及添加量对Mo的拉伸性能和显微组织的影响.结果表明,添加合金元素Zr、Ti大大提高了Mo的力学性能.合金元素Zr以纯Zr形式加入较以ZrH2形式为佳,其添加量在0.1%(质量分数,下同)时,合金性能最高.元素Zr仅有极少部分固溶到Mo基体中,大部分与合金中少量氧结合以ZrO2粒子相存在.合金元素Ti则以TiH2的方式添加为佳,添加量为0.8%时合金性能最高.元素Ti一部分固溶到Mo基体中,另一部分与Mo及合金中的少量氧结合以MoxTiO2复合氧化物粒子相存在.     

低Nb含量Ti-Mo-Nb-Zr-Sn BCC低弹性模量固溶体合金的成分设计

依据BCC结构中的"团簇加连接原子"模型确定Ti-Mo二元团簇式[MoTi14]Mo1为基础成分式,根据合金化组元Sn、Zr和Nb与基体Ti的混合焓实现其在基础成分式中的组元替换,从而形成多元成分式[(Mo,Sn)(Ti,Zr)14]Nb1。利用铜模吸铸快冷技术制备d 6 mm合金棒状样品,并对其进行950℃保温2 h并水淬。组织结构分析和拉伸力学性能结果表明:低模量Sn、Zr和Nb分别取代基础成分式中高模量的Mo时形成的三元BCCβ-Ti合金结构稳定,且具有较低的弹性模量;当Mo0.5Sn0.5占据团簇心部,Nb作为连接原子,Zr替代部分Ti时形成的低Nb含量的β-Ti合金[(Mo0.5Sn0.5)(Ti13Zr)]Nb1(Ti68.10Mo5.25Sn6.50Zr9.98Nb10.17,质量分数,%)具有最低的弹性模量(为43 GPa),且断裂强度σb为569 MPa,应变ε为5.6%。     

微量合金元素Ti、Zr对Mo金性能和显微组织的影响

采用粉末冶金法制备Mo-Zr、Mo-Ti合金,研究了Zr、Ti的添加方式及添加量对Mo的拉伸性能和显微组织的影响。结果表明,添加合金元素Zr、Ti大大提高了Mo的力学性能。合金元素Zr以纯Zr形式加入较以ZrH2形式为佳,其添加量在0.1%（质量分数,下同）时,合金性能最高。元素Zr仅有极少部分固溶到Mo基体中,大部分与合金中少量氧结合以ZrO2粒子相存在。合金元素Ti则以TiH2的方式添加为佳,添加量为0.8%时合金性能最高。元素Ti一部分固溶到Mo基体中,另一部分与Mo及合金中的少量氧结合以MoxTiyOz复合氧化物粒子相存在。     

自蔓延高温合成钴-钛系多孔合金

采用自蔓延高温合成制备了Co-Ti多孔体新型人体骨、关节材料。以Ti粉和Co粉按原子比Ti∶Co=1∶1与Ti∶Co=2∶12种配比的原料,在10Pa负压条件下,500℃预热2min点燃进行自蔓延合成反应。对反应产物进行XRD分析和SEM观察及力学性能测试。结果表明,2种合成产物分别为单相CoTi和CoTi2。CoTi的结构和力学性能比CoTi2优越。其孔隙率为40.9%,抗压强度308MPa,抗折强度134MPa,弹性模量11.6GPa,与人体骨、关节具有很好的力学性能相容性。因此用SHS法制备的CoTi多孔合金有望作为一种新型人体植入材料获得开发应用。     

Characteristics and lacquer adhesion on dip and CDC chromium passivated tinplate

Chromium passivation and lacquering are typically used to improve the corrosion resistance of tinplate in packed food. In this work, the nature of the chromium passivation layer formed during dip or CDC passivation treatments, as a function of operational parameters, and its influence on lacquer adhesion, was investigated using electrochemical polarisation, XPS, Auger and lacquer peel-off tests. It was found that dip passivated tinplate provide the best lacquer adhesion, and that the adhesion on CDC treated tinplate could be improved by buffering or lowering the pH of the chromium (VI) solution.     

De-alloying of type 316 stainless steel in hot, concentrated sodium hydroxide solution

The formation of “nickel” layers on austenitic stainless steel in strong caustic solutions was reported in 1979. We now report a detailed study that clarifies the nature of this de-alloying process and establishes firm links with other metal-environment systems that show de-alloying and associated stress corrosion cracking. De-alloying of iron from 316SS in 50% NaOH at 140 °C proceeds only as far as a solid solution with a Ni/Fe atomic ratio of ca. 1.3 (56 at.% Ni if we neglect the other elements present). Chromium is mostly dissolved and/or reprecipitated during this process. X-ray diffraction shows that the residue is a solid solution of intermediate composition, not a mixture of pure Ni and stainless steel. The removal of only half the iron conveniently explains why the de-alloyed layer is a connected porous network. Electrode capacitance measurements and FEG-SEM examination show that the de-alloyed layer has extremely fine nanoporosity.     

Mechanism of cathodic delamination control of zinc-aluminum phosphate pigment in waterborne coatings

The propagation of the cathodic delamination and blistering was studied for different waterborne paint systems, with or without the zinc aluminum phosphate (ZAP) pigment. The mechanism by which ZAP reacts at the metal-coating interface to improve coating performance against cathodic delamination and blister formation was investigated by means of scanning acoustic microscopy (SAM), pull-off test and surface analysis. The presence of the pigment clearly enhanced the adhesion and delamination resistance of the coating upon immersion. It has been evidenced how the pH buffer properties of the ZAP pigment play an important role in reducing the advancement of the delamination front. A compact film constituted of zinc and sodium phosphates was found, on the substrate surface, solely within the delaminated area. The precipitation of this phosphate layer on the cathodic sites is thought to polarize the cathodic reaction, contributing to slowing down the delamination reaction.     

Pit-to-crack transition in pre-corroded 7075-T6 aluminum alloy under cyclic loading

Pit-to-crack transition experiments were conducted on 1.600 mm and 4.064 mm 7075-T6 aluminum alloy. Specimens were corroded using a 15:1 ratio of 3.5% NaCl solution and H₂O₂ prior to fatigue loading. Cracks originating from corrosion pits were visually investigated in order to understand how pit-to-crack transitions occur.All prior corroded specimens in the study fractured from cracks associated with pitting. Pit-to-crack transition was successfully acquired visually. Corroded 7075-T6-4.064 mm specimens experienced more of an overall fatigue life reduction than 7075-T6-1.600 mm specimens. Results indicated that quantities such as pit surface area and surrounding pit proximity are as important as pit depth in determining when and where a crack will form.     

NiAl－Fe金属间化合物合金的正电子寿命谱

测量了塑性金属间化合物合金Ｎｉ（５０）Ａｌ（３０）Ｆｅ（２０），Ｎｉ（５０）Ａｌ（２０）Ｆｅ（３０）和Ｎｉ（６０）Ａｌ（２０）Ｆｅ（２０）单晶和多晶的正电子寿命谱．基于正电子寿命谱的特征参数引入了正电子双区域捕获模型，并讨论了这些合金微观结构与力学性能之间的关系．     

NiAl—Fe金属间化合物合金的正电子寿命谱

测量了塑性金属间化合物合金Ｎｉ５０Ａｌ３０Ｆｅ２０，Ｎｉ５０Ａｌ２０Ｆｅ３０，Ｎｉ６０Ａｌ２０Ｆｅ２０单晶和多晶的正电子寿命谱。基于正电子寿命谱的特征参数引入了正电子双区域捕获模型，并讨论了这些合金微观结构与力学性能之间的关系。     

Effects of alloy and solution chemistry on the fracture of passive films on austenitic stainless steel

The Taguchi analysis method was used to simultaneously study the effects of alloy chemistry, pH, and halide ion concentrations on the fracture of electrochemically grown passive films using a nanoindentation technique. Three austenitic stainless steels, 304L, 316L, and 904L were potentiostatically polarized in hydrochloric acid solutions. The fracture load was dominated primarily by alloy chemistry. Passive films mechanically weaken as the atomic iron concentration increases in the film. Prolonged anodic ageing time increases the fracture load of passive films.     

Corrosion resistance properties of glow-discharge nitrided AISI 316L austenitic stainless steel in NaCl solutions

Glow-discharge nitriding treatments can modify the hardness and the corrosion resistance properties of austenitic stainless steels. The modified layer characteristics mainly depend on the treatment temperature. In the present paper the results relative to glow-discharge nitriding treatments carried out on AISI 316L austenitic stainless steel samples at temperatures ranging from 673 to 773 K are reported. Treated and untreated samples were characterized by means of microstructural and morphological analysis, surface microhardness measurements and corrosion tests in NaCl solutions. The electrochemical characterization was carried out by means of linear polarizations, free corrosion potential-time curves and prolonged crevice corrosion tests. Nitriding treatments performed at higher temperatures (>723 K) can largely increase the surface hardness of AISI 316L stainless steel samples, but decrease the corrosion resistance properties due to the CrN precipitation. Nevertheless nitriding treatments performed at lower temperatures (?723 K) avoid a large CrN precipitation and allow to produce modified layers essentially composed by a nitrogen super-saturated austenitic metastable phase (S-phase) that shows high hardness and very high pitting and crevice corrosion resistance; at the same polarization potentials the anodic current density values are reduced up to three orders of magnitude in comparison with untreated samples and no crevice corrosion event can be detected after 60 days of immersion in 10% NaCl solution at 328 K.     

Corrosion behavior of glassy Ni55Co5Nb20Ti10Zr10 alloy in 1 N HCl solution studied by potentiostatic polarization and XPS

Corrosion resistance of glassy Ni₅₅Co₅Nb₂₀Ti₁₀Zr₁₀ (at.%) alloy in 1 N HCl solution was investigated with respect to the electrochemical behavior and the compositions of the passive film and the underlying alloy surface just below the passive film. The potentiostatic polarization curve indicated that the alloy was spontaneously passivated with a low passive current density of the order of 10⁻³ A m⁻². The quantitative X-ray photo-electron spectroscopy (XPS) analysis revealed that the thickness of the surface film increased linearly with an anodizing ratio of 1.5 nm V⁻¹. The high corrosion resistance of the glassy alloy was due to the formation of niobium, titanium and zirconium-enriched passive film. The growth mechanism of the passive films is also discussed.     

The nature of the surface film on steel treated with cerium and lanthanum cinnamate based corrosion inhibitors

The corrosion inhibition mechanisms of new cerium and lanthanum cinnamate based compounds have been investigated through the surface characterisation of the steel exposed to NaCl solution of neutral pH. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy was used to identify the nature of the deposits on the metal surface and demonstrated that after accelerated tests the corrosion product commonly observed on steel (i.e. lepidocrocite, γ-FeOOH) is absent. The cinnamate species were clearly present on the steel surface upon exposure to NaCl solution for short periods and appeared to coordinate through the iron. At longer times the Rare Earth Metal (REM) oxyhydroxide species are proposed to form as identified through the bands in the 1400-1500 cm⁻¹ region. These latter bands have been previously assigned to carbonate species adsorbed onto REM oxyhydroxide surfaces. The protection mechanism appears to involve the adsorption of the REM-cinnamate complex followed by the hydrolysis of the REM to form a barrier oxide on the steel surface.