刘建涛
,
林鑫
,
吕晓卫
,
陈静
,
黄卫东
金属学报
采用激光立体成形技术制备了从Ti到Ti2AlNb成分连续渐变、外形规则、高度为17 mm的梯度材料. 分析了梯度材料的组织及相结构演变规律和硬度变化规律. 随着Al和Nb成分的提高,Ti-Ti2AlNb功能梯度材料的相呈现α' → α+β → α+α' → α' → α+β → α+β/B2+α2 → β/B2+α2 → β/B2 →B2+ α2+O→ B2的演变过程, 实现了由$α$型钛合金经过α+β型及β型钛合金向Ti2AlNb基合金的转变. 硬度值HV从底部纯Ti的170连续
渐变到顶端Ti2AlNb的470. 基于钛合金富Ti区非平衡相图, 并结合Al和Nb元素在钛合金中对α, β和α2稳定性的影响分析, 对梯度材料在激光立体成形过程中的相演化过
程进行了解释.
关键词:
激光立体成形
,
Titanium
,
Ti2AlNb
,
Functionally graded materials
,
Phase transformations
Xu Shao
,
Zhou Zhiyu
,
Gao Manman
,
Zou Changye
,
Che Yinglin
,
Cody Bünger
,
Zou Xuenong
,
Zhou Lei
材料科学技术（英文）
doi:10.1016/j.jmst.2016.08.009
Titanium (Ti) nanorods fabricated using selective corrosion of Ti substrate by anodic technology show better biocompatibility with pre-osteoblast cells. The current study investigated the response of the murine pre-osteoblast cell MC3T3-E1 on Ti nanorod topography and untreated Ti surfaces by means of examination of the morphology and osteogenic differentiation responsible for the pre-osteoblast reaction. The morphology of MC3T3-E1 cells was observed using scanning electron microscopy, and alkaline phosphatase (ALP) activity was measured using a colorimetric assay after incubation for 7, 14, and 21 days. The expression of three osteogenic differentiation markers including ALP, osteocalcin (OCN), and collagen type 1A1 (COL1A1) and two transcription factors including runt related transcription factor 2 (Runx2) and osterix (Osx) at different time points was detected using real-time polymerase chain reaction analysis in both groups. Osx was used to confirm the protein level. The results showed that Ti nanorod surfaces provided prolonged higher levels of ALP activity compared with unmodified Ti surface on the 14th and 21st days. Gene expression analysis of ALP, OCN, and COL1A1 showed significant upregulation with modified nanorod topography after incubation for 14 and 21 days. Osteogenic transcription factors of Runx2 and Osx exhibited changes consistent with the osteogenic differentiation markers, and this may contribute to the persistently active differentiation of MC3T3-E1 cells in the Ti nanorod group. These results demonstrated that the current nanostructured surface may be considered bioadaptive topography to control cellular behaviors and osteoblast differentiation. The in vivo performance and applicability are further required to investigate osseointegration between implant and host bone in the early stages for prevention of aseptic implant loosening.
关键词:
Titanium
,
Nanorods
,
Osteointegration
,
Osteoblast differentiation
S. Candan
金属学报(英文版)
Most of dental implants are made from titanium or titanium based alloys. However, one of the drawback of such implants is high cost due to the technological difficulties in casting method or machining. In this work, powder injection moulding (PIM) method has been used in order to explore lower cost implants without minimising the biocorrosion resistance of the titanium. Corrosion resistance of titanium specimens, produced by powder injection moulding method (PIM-Ti), in physiologic serum and artificial saliva was investigated. Commercially pure bulk Ti (CP-Ti) was used as control sample. Surface oxidation was also carried out to both PIM-Ti and CP-Ti samples. Microstructure and corrosion resistance were investigated using microhardness, X-ray diffraction (XRD), scanning electron microscopy (SEM) and potentiodynamic polarization experiments. Resulting microstructure of PIM-Ti samples contained porosity as compared to CP-Ti control samples. Microhardness of PIM-Ti samples varied with varying applied load whereas it was free from applied load for CP-Ti control samples. Polarisation measurements and SEM analysis revealed that corrosion behaviour of PIM-Ti was reasonably as good as CP-Ti both in as-produced and oxidized conditions in physiologic serum and artificial saliva in spite of its porous structure.
关键词:
Titanium
Si-Young Sung
,
Bong-Jae Choi
,
Beom-Suck Han
,
Han-Jun Oh
,
Young-Jig Kim
材料科学技术（英文）
The alpha-case formation reactions between Ti and investment molds (Al2O3, ZrSiO4, ZrO2, CaO stabilized ZrO2) were evaluated in a plasma arc melting furnace. Regardless of thermodynamic approaches, there were distinct alpha-case formations. The reaction products were characterized by electron probe micro-analysis and transmission electron microscopy. The α-case generation between Ti and Al2O3 mold was not able to be explained by the conventional α-case formation mechanism, which is known to be formed by the interstitials, especially oxygen dissolved from mold materials. However, from our experimental results and thermodynamic calculations, it was confirmed that the α-case is formed not only by an interstitial element but also by substitutional metallic elements dissolved from mold materials. Our newly established α-case formation mechanism will surely lead to a variety of significant applications of the α-case controlled Ti casting.
关键词:
Titanium
,
null
,
null
,
null
F.T.Cheng
材料科学技术（英文）
The results and main findings of studies reported in the literature in relation to the deposition of calcium phosphate on Ti in simulated body fluids are summarized. The effects of the surface hydroxyl groups and the sign of surface charge on the nucleation of calcium phosphate are reviewed. One major controversy among the conclusions of different studies is the order of adsorption of the calcium ions and the phosphate ions in the initial stage of immersion. A simple model based on the amphoteric nature of the hydroxyl groups on Ti is proposed in an attempt to delineate the nucleation process for calcium phosphate on Ti in simulated body fluids. HPO42- ions interact with the hydroxyl groups via ion exchange and/or electrostatic attraction, and Ca2+ ions, via electrostatic attraction only. There is no preferential order of adsorption. Seemingly inconsistent results in different studies possibly arise from different prior treatments of the samples, which affect the adsorption properties.
关键词:
Titanium
,
null
,
null
,
null
Tan Guoxin
,
Ouyang Kongyou
,
Wang Hang
,
Zhou Lei
,
Wang Xiaolan
,
Liu Yan
,
Zhang Lan
,
Ning Chengyun
材料科学技术（英文）
doi:10.1016/j.jmst.2016.07.012
The objective of this study was to determine the role of functional groups of silane coupling on bioactive titanium (Ti) surface by electrochemical deposition, and calcium phosphate (CaP) coating, as well as bone cell adhesion and proliferation. Methyl group (—CH3), amino group (—NH2), and epoxy group (—glyph name—C(O)C) were introduced onto the bioactive Ti surface using self-assembled monolayers (SAMs) with different silane coupling agents as molecular bridges. The effect of the surface functional groups on the growth features of the CaP crystals was analyzed (including chemical compositions, element content, minerals morphology and crystal structure etc.). CH3-terminated SAMs showed a hydrophobic surface and others were hydrophilic by contact angle measurement; NH2-terminated SAMs showed a positive charge and others were negatively charged using zeta-potential measurement. Scanning electron microscopy results confirmed that flower-like structure coatings consisting of various pinpoint-like crystals were formatted by different functional groups of silane coupling, and the CaP coatings were multicrystalline consisting of hydroxyapatite (HA) and precursors. CaP coating of CH3-terminated SAMs exhibited more excellent crystallization property as compared to coatings of —NH2 and —C(O)C groups. In vitro MC3T3-E1 cells adhesion and proliferation were performed. The results showed that CaP coatings on silane coupling functionalized surfaces supported cell adhesion and proliferation. Thus, these functional groups of silane coupling on Ti can form homogeneous and oriented nano-CaP coatings and provide a more biocompatible surface for bone regeneration and biomedical applications.
关键词:
Silane coupling
,
Molecular bridge
,
Calcium phosphate coatings
,
Titanium
,
Electrochemical deposition
周晓兆
,
刘艳
,
孟祥举
,
申宝剑
,
肖丰收
催化学报
doi:10.1016/S1872-2067(12)60638-X
以天然凹凸棒石为硅源、铁源和钛源,一步合成了Fe/Ti-ZSM-5分子筛.X射线衍射、扫描电镜和N2吸附等温线测定结果表明,所合成的样品具有良好的结晶度和较大的比表面积；NH3程序升温脱附和H2程序升温还原结果表明,该样品具有强的酸性和氧化还原性能.更为重要的是,与常规方法制备的ZSM-5沸石相比,Fe/Ti-ZSM-5在催化裂解原料油(LGO,加拿大)的测试中,丙烯的产率提高0.21％,总轻烯烃的产率提高0.33％.由此可见,Fe与Ti物种在ZSM-5沸石分子筛中的存在有利于提高轻烯烃的产率,有望在石油炼制过程中提高烯烃产率.
关键词:
天然凹凸棒石
,
铁
,
钛
,
ZSM-5
,
沸石分子筛
,
催化裂化
,
丙烯
Ruihua HU
,
Montasser M.Dewidar
,
Hyo-Jin KIM
,
Jae-Kyoo LIM
,
null
材料科学技术（英文）
In order to improve the wear resistance of Ti-6Al-4V, different amounts of Si3N4 powder were added into the alloy powder and sintered at 1250℃. Porous titanium alloy with higher wear resistance was successfully fabricated. At sintering temperature, reaction took place and a new hard phase of Ti5Si3 formed. The mechanical properties of the fabricated alloys with different amounts of Si3N4 addition were investigated. The hardness of Ti-6Al-4V, which is the index of wear resistance, was increased by the addition of Si3N4. Amounts of Si3N4 addition have very significant influences on hardness and compressive strength. In present study, titanium alloy with 5 wt pct Si3N4 addition has 62% microhardness and 45% overall bulk hardness increase, respectively. In contrast, it has a 16.4% strength reduction. Wear resistance was evaluated by the weight loss during wear test. A new phase of Ti5Si3 was detected by electron probe microanalyzer (EPMA) and X-ray diffraction (XRD) method. The original Si3N4 decomposed during sintering and transformed into titanium silicide. Porous structure was achieved due to the sintering reaction.
关键词:
Ti-6Al-4V
,
alloy
,
Wear
,
Sintering
,
reaction
Hongyan MA
,
Maocai WANG
,
Weitao WU
材料科学技术（英文）
In order to improve the surface hardness and wear resistance of Ti and Ti alloy components, an oxygen permeation treatment (OPT) was developed. The oxygen permeation behaviors of three Ti alloys, TA2, TB5 and TC11, treated in air with O-P medium at high temperature have been studied. The results show that the O-P treatment can significantly improve the surface hardness of Ti alloys. The oxidation mass-gain of β-Ti alloy (TB5) is much higher than α-Ti alloy (TA2) under the same condition, while α+βTi alloy (TC11) is the lowest. All the Ti alloys treated at this condition produce two surface layers: the outer layer consists mainly of TiO¬2, as well as trace of other oxides, and the inner layer consists of a Ti-O interstitial solid solution formed by the diffusion of oxygen in α crystal lattice. Thick scales of βTi alloy (TB5) are easily formed depending mainly on the poor solid solution content of oxygen, while deep solution layer can be formed since partial β phase has been transformed into α phase. The scales of α-βTi alloy (TC11) are very thin and compact. Aluminum-rich zone, as well as deficient zone, is found in oxide layers. A crystallographic characterization of oxygen solution layer has been performed and evaluated by crystallographic lattice constant.
关键词:
Microstructure
,
null
,
null
,
null
J.Rassizadehghani
,
H.Najafi
,
M.Emamy
,
G.Eslami-Saeen
材料科学技术（英文）
The influence of microalloying additions on the mechanical properties of a low-carbon cast steel containing combinations of V, Nb, and Ti in the as-cast condition was evaluated. Tensile and hardness test results indicated that good combinations of strength and ductility could be achieved by V and Nb additions. While the yield strength and UTS (ultimate tensile strength) increased up to the range of 378–435 MPa and 579–596 MPa, respectively in the microalloyed heats, their total elongation ranged from 18% to 23%. The presence of Ti, however, led to some reduction in the strength. Microstructural studies including scanning electron microscopy (SEM) and optical microscopy revealed that coarse TiN particles were responsible for this behavior. The Charpy impact values of all compositions indicated that microalloying additions significantly decreased the impact energy and led to the dominance of cleavage facets on the fracture surfaces. It seems that the increase in the hardness of coarse ferrite grains due to the precipitation hardening is the main reason for brittle fracture.
关键词:
Cast steel
,
null
,
null
,
null
,
null
