Layered structure of cast titanium surface

The present study concerns the surface layered structure of the cast Ti. A commercial Ti was cast into a mold which was made of a phosphate-bonded Al2O3/SiO2 investment. Elemental analyses of the interfacial zone of the casting were made under an electron probe micro-analyzer. The interfacial zone was composed of four layers: the outermost reaction or casting burn layer, the second layer of an O-and Al-stabilized alpha case, the third layer in which Si, P, O, and C were inhomogeneously concentrated, and the fourth layer which consisted of acicular or plate-like crystals. It was observed that the larger the cast volume and the higher the mold temperature, the thicker became each layer and the coarser became the acicular grains. Probably, the layered structure was formed through decomposition of reducible species in the burnout investment and diffusion of the resulting elements into the casting.     

激光焊接间距对牙科铸造纯钛性能影响的实验研究

目的:研究激光焊接铸造纯钛时不同的焊接间距对纯钛性能的影响。方法:将铸造钛试样按照焊接间距的大小分为4组:0.00、0.25、0.50、1.00mm组,肉眼、扫描电镜观察焊缝区外观,测试焊件的抗拉强度,整铸件为对照组。结果:各试验组焊缝区显示全层焊透、无明显气孔等焊接缺陷,断口电镜显示为延展性(韧窝)与脆性(气孔、裂纹)共存的形貌。各实验组与对照组间抗拉强度方差分析结果显示差异无显著性(P>0.05)。结论:不同的焊接间距对铸钛的机械性能无明显影响。     

钛激光气体氮化改性种植体的研究

目的利用激光气体氮化工艺在医用纯钛表面制备TiN改性层,增强医用钛的表面性能,测试改性层的组织、成分和硬度。方法采用2 kW Nd:YAG激光器对置于特制导光可控气氛反应室中的医用纯钛辐照,在纯度为99.995%的氮气中进行激光气体氮化过程。测试分析材料改性前后的显微组织、成分和硬度。结果在医用钛的表面制备了厚度约400 μm的TiN梯度改性层,氮化层与基体界面呈良好的冶金结合。沿着改性层截面方向,显微硬度逐渐减小。结论采用激光气体氮化技术可以在医用钛表面制备致密的TiN增强金属复合材料梯度氮化层,氮化层内部TiN增强相呈梯度分布。     

Adhesive bonding of composite material to cast titanium with varying surface preparations

The purpose of the present study was to evaluate the surface preparation effects of eight metal conditioners and an adhesive system on bonding between a prosthodontic composite material and cast titanium. Eight primers designed for conditioning base metal alloys (Acryl Bond, All-Bond 2 Primer B, Alloy Primer, Cesead II Opaque Primer, Eye Sight Opaque Primer, Metafast Bonding Liner, Metal Primer II, and MR Bond) as well as a surface modification technique (Siloc) were assessed. Disk specimens cast from titanium (T-Alloy H) were either primed with one of the eight primers or treated with the Siloc system, and then bonded with a light-activated composite material (Artglass). Bond durability was evaluated by thermocycling (4 and 60 degrees C, 1 min each, 20, 000 cycles). After thermocycling, two groups either primed with the Cesead II Opaque Primer material or treated with the Siloc system exhibited significantly greater bond strength (20.0 and 19.0 MPa) than the other groups (0.2-12.6 MPa, P < 0.05). These two systems are considered to be useful for improving bonding between the titanium and the composite material tested.     

Structure, castability and mechanical properties of commercially pure and alloyed titanium cast in graphite mould

This report is a study of structure, castability, mechanical properties as well as corrosion behaviour of titanium doped with up to 5 weight percentage (wt%) of a series of alloy elements, including Ta, Mo, Nb, Hf, Zr, Sn, Bi and Ag. The results indicate that, with addition of 1 wt% alloy element, Bi and Mo were most effective in enhancing the castability of titanium. With more alloy elements added, the castability values of most alloys more or less decreased. Except Ti-Mo system, all Ti alloys with a fine acicular morphology had the same crystal structure (hcp) as that of c.p. Ti with a typical lath type morphology. When 3 wt% or more Mo was added, a finer orthorhombic alpha' phase was formed. The microhardness and bending strength values of Ti alloys were all higher than those of c.p. Ti. Among all alloys, Ti-Mo system exhibited the highest hardness and strength level. For a certain alloy, the bending strength did not necessarily increase with its alloy content. Except Ti-5Zr and Ti-Mo alloys, the bending moduli of most alloy systems were not much different from that of c.p. Ti. All alloys showed an excellent resistance to corrosion in Hanks' solution at 37 degrees C.     

Effect of toothbrushing on titanium surface: an approach to understanding surface properties of brushed titanium.

OBJECTIVES: This in vitro study aimed to characterize the surface morphology and composition of tooth-brushed titanium casting and thereby to elucidate interactions between the metal and abrasive material in dentifrice. METHODS: Specimens were cast from CP Ti ingots and then mirror-finished. Two fluoride-free toothpastes containing crystalline CaHPO4.2H2O and amorphous SiO2 particles as abrasive were slurried with distilled water (15 g/30 mL). While toothbrushes were reciprocated at 120 strokes/min for 350,400 strokes, the specimens were brushed with the respective slurries under a load of 2.45 N. The brushed and non-brushed surfaces were characterized by means of SPM, EPMA, and XPS. SPM data were analyzed using one-way ANOVA, followed by post hoc Tukey test (p<0.01). RESULTS: Irrespective of toothpastes, toothbrushing had a significant influence on surface roughness. The CaHPO4.2H2O-containing paste produced much rougher surface than the SiO2-containing paste. Both the surfaces were chemically altered due to reactions with the respective abrasive materials. Abrading chips had dimensions of micron to submicron order. A number of chips were attached to abrasive particles. SIGNIFICANCE: The alterations of surface morphology and composition may affect biological responses of titanium in the oral environment. Dentifrice with lower abrasivity might be advisable for daily oral hygiene practice of patients with dental titanium devices.     

Effects of a modified sandblasting surface treatment on topographic and chemical properties of titanium surface

A modified sandblasting surface treatment (a noncoating, roughening surface modification of dental implants) has been developed that will overcome the defects of conventional coating techniques. To verify the feasibility and reliability of this method at the chemical and topographic levels, scanning electron microscopy, x-ray diffraction, and a titanium ion releasing test were used; the topography of titanium surface, the embedding of sandblasting particles, nonpollution of heteroelements, and anticorrosiveness of titanium were criteria. Results showed that the rough surface created by sandblast was rather irregular, full of sharp tips and many embedded sandblast particles, and its corrosive rate was increased. These characteristics were modified by oxalic acid attack; the contour of the rough surface became more regular and round, the embedded particles and the heteroelement pollution were thoroughly removed, and the Ti corrosive rate decreased dramatically. Oxalic acid attack modification also created numerous secondary micropores (2.0-micron diameter) on the basis of sandblasted surface macrotexture. This modified sandblasting surface treatment is feasible and reliable to apply to dental implants and does not decrease the biocompatibility of titanium.     

激光焊接铸造纯钛焊缝薄膜材料的力学性能研究

目的:应用激光干涉应变计法研究激光焊接铸造纯钛焊缝薄膜材料的力学性能。方法:将激光焊接后的纯钛板按焊缝距离的不同分为0.00、0.25、0.50 mm焊接组和对照组(无焊接),把焊接后的纯钛板和母材线切割成小试样(60 mm×20mm×1 mm),X线探伤筛选后,对合格小试样运用激光干涉应变计法进行拉伸试验,测定材料的抗拉强度并得出应力、应变曲线。结果:随着焊缝距离的增大,3组试样抗拉强度分别为(492.16±33.19)MPa、(488.09±43.18)MPa、(558.45±10.80)MPa,与母材抗拉强度(532.15±11.62)MPa无显著性差别(P>0.05)。0.00 mm焊缝焊接组与0.25 mm焊缝焊接组拉伸过程中无明显颈缩,拉伸应力、应变曲线显示其塑性形变量明显减少,延伸率显著下降。0.5 mm焊缝焊接组焊件变形较大,拉伸过程中颈缩明显,拉伸应力、应变曲线显示其塑性形变量减少,延伸率下降。结论:焊缝薄膜材料的抗拉强度与母材无显著性差异,但塑性形变量和延伸率均不及母材。焊接过程中焊缝间隙较小时容易出现脆性断裂;焊接间隙较大时焊接精度随之下降。     

Effect of surface reaction layer on grindability of cast titanium alloys.

OBJECTIVE: The purpose of this study was to investigate the effect of the cast surface reaction layer on the grindability of titanium alloys, including free-machining titanium alloy (DT2F), and to compare the results with the grindability of two dental casting alloys (gold and Co-Cr). METHODS: All titanium specimens (pure Ti, Ti-6Al-4V and DT2F) were cast using a centrifugal casting machine in magnesia-based investment molds. Two specimen sizes were used to cast the titanium metals so that the larger castings would be the same size as the smaller gold and Co-Cr alloy specimens after removal of the surface reaction layer (alpha-case). Grindability was measured as volume loss ground from a specimen for 1 min using a handpiece engine with a SiC abrasive wheel at 0.1 kgf and four circumferential wheel speeds. RESULTS: For the titanium and gold alloys, grindability increased as the rotational speed increased. There was no statistical difference (p>0.05) in grindability for all titanium specimens either with or without the alpha-case. Of the titanium metals tested, Ti-6 Al-4V had the greatest grindability at higher speeds, followed by DT2F and CP Ti. The grindability of the gold alloy was similar to that of Ti-6 Al-4V, whereas the Co-Cr alloy had the lowest grindability. SIGNIFICANCE: The results of this study indicated that the alpha-case did not significantly affect the grindability of the titanium alloys. The free-machining titanium alloy had improved grindability compared to CP Ti.     

钛铸件与三种钛瓷粉结合强度的对比研究

目的 :观察钛铸件与VitaTitankeramik、TiBond和NoritakeTi2 2三种钛专用瓷粉的结合强度 ,分析钛/瓷结合强度的影响因素。方法 :根据ISO 9693标准 ,运用三点弯曲方法对钛 /瓷和Ni -Cr/瓷的结合强度进行测试 ,并对钛 /瓷结合界面进行SEM /EDS观察与分析。结果 :钛 /TiBond结合强度 ( 3 0 .96± 3 .0 6)MPa、钛 /VitaTi tankeramik结合强度 ( 3 5 .18± 3 .0 6)MPa ,钛 /NoritakeTi2 2结合强度 ( 3 8.5 4± 3 .0 6)MPa ,均大于ISO所要求的基本值 2 5MPa ,但仍明显小于Ni-Cr/瓷的结合强度 ( 4 8.3 5± 3 .0 6)MPa(P <0 .0 1)。钛 /VitaTitankeramik界面存在大量的孔隙 ,瓷对钛的浸润性较差。钛 /NoritakeTi2 2界面瓷与钛基体相互交错 ,结合紧密。结论 :钛 /瓷结合强度可满足临床需要 ,但仍需进一步改善     

Three-point bending strength of ceramics fused to cast titanium

Titanium requires special ceramic systems for veneering. This study compared the three-point bending strength of three commercially available titanium ceramic systems with a NiCr-alloy with conventional ceramics. Three-point bend specimens 25 × 5 × 0.5 mm were cast from polyethylene patterns. After α-case removal, they were veneered with 8 × 5 × 1 mm of ceramics at the center of the bar. Specimens were tested in a universal testing machine without ageing, after thermocycling, and after 90 d storage in an electrolyte solution. Titanium-ceramic systems were found to have a significantly lower bond strength in comparison to the NiCr-ceramic system. One of the titanium ceramic systems had a significantly lower bond strength in comparison to the other systems investigated. It could be concluded that bonding between titanium and ceramics is obtainable; however, the achievable bond strengths did not match the NiCr-ceramic control.     

A new device to improve cast articulation procedures

Achieving accurate cast articulation is a challenge for dentists and dental technicians. To ensure accuracy, a convenient, efficient, and predictable technique is needed to stabilize dental casts together, even when the casts are wet. The purpose of this article is to describe the use of a device specifically designed to secure casts together during the articulation process.     

Dynamic mechanical properties of straight titanium alloy arch wires

Eight straight-wire materials were studied: an orthodontic titanium-molybdenum (Ti-Mo) product, TMA; three orthodontic nickel-titanium (Ni-Ti) products, Nitinol, Titanal, and Orthonol; three prototype alloys, a martensitic, an austenitic, and a biphasic alloy; and a hybrid shape-memory-effect product, Biometal. Each wire was prepared with a length-to-cross-sectional area of at least 3600 cm-1. With an Autovibron Model DDV-II-C used in the tensile mode, each sample was scanned from -120 to +200 degrees C at 2 degrees C/min. From the data base, plots of the log storage modulus, log tan delta, and percent change in length vs. temperature were generated. Results showed that the dynamic mechanical properties of the alloys within this TI system are quite different. The Ti-Mo alloy, TMA, was invariant with temperature, having a modulus of 7.30 x 10(11) dyne/cm2 (10.6 x 10(6) psi). The three cold-worked alloys--Nitinol, Titanal, and Orthonol--appeared to be similar, having a modulus of 5.74 x 10(11) dyne/cm2 (8.32 x 10(6) psi). The biphasic shape-memory alloy displayed a phase transformation near ambient temperature; whereas the hybrid shape-memory product, Biometal, underwent a 3-5% change in length during its transformation between 95 and 125 degrees C. Among the Ni-Ti wires tested, several different types of alloys were represented by this intermetallic material.     

钛铸件的气孔

钛铸件气孔是铸钛中普遍存在的一个问题。本就气孔产生的原因、测量方法及影响因素作一综述目前尚没有完全有效的方法来克服它。     

医用钛及钛合金表面处理技术现状

钛及钛合金是安全性高的生物材料之一,随着铸造技术和加工技术的进步,钛及钛合金在口腔医学领域内日益被广泛应用。然而其表面硬度低、耐磨性差、生物惰性等是作为医用材料不容忽视的问题,通过对钛及钛合金表面氧化、氮化、激光处理可以显著改善钛及钛合金的表面性能,本文综合评述了多种表面处理技术的优点,对多种表面处理技术综合应用将是今后的研究方向。     

氮化钛镀膜对纯钛铸件表面耐磨性的影响

目的 研究氮化钛(TiN)镀膜对纯钛铸件表面硬度和耐磨性的影响.方法 应用闭合场非平衡磁控溅射(CFUBMS)方法在纯钛铸件表面制备TiN薄膜,显微硬度仪测量纯钛铸件表面硬度,磨擦磨损试验评估其耐磨性.结果 纯钛铸件表面应用CFUBMS方法制备TiN薄膜后,显微硬度明显增加,磨擦系数和磨损体积明显减小.结论 CFUB...