Bioactive borate glass coatings for titanium alloys

Bioactive borate glass coatings have been developed for titanium and titanium alloys. Glasses from the Na(2)O-CaO-B(2)O(3) system, modified by additions of SiO(2), Al(2)O(3), and P(2)O(5), were characterized and compositions with thermal expansion matches to titanium were identified. Infrared and X-ray diffraction analyses indicate that a hydroxyapatite surface layer forms on the borate glasses after exposure to a simulated body fluid for 2 weeks at 37 degrees C; similar layers form on 45S5 Bioglass((R)) exposed to the same conditions. Assays with MC3T3-E1 pre-osteoblastic cells show the borate glasses exhibit in vitro biocompatibility similar to that of the 45S5 Bioglass((R)). An enameling technique was developed to form adherent borate glass coatings on Ti6Al4V alloy, with adhesive strengths of 36 +/- 2 MPa on polished substrates. The results show these new borate glasses to be promising candidates for forming bioactive coatings on titanium substrates.     

Electrochemical preparation of protective oxide coatings on titanium surgical alloys

This paper reports a novel electrochemical method for the preparation of protective titanium oxide coatings to improve the corrosion resistance and biocompatibility of the Ti6A14V surgical alloy. Scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), Auger electron spectroscopy (AES), and the X-ray diffraction technique were used to characterize the structure and the chemical composition of the oxide coatings.In vitro electrochemical corrosion studies were also conducted to assess the effectiveness of the oxide coatings in reducing the metal-ion release from Ti6A14V. The results suggest that the coating process may provide an effective means for improving the corrosion resistance and biocompatibility of titanium surgical alloys under physiological conditions.     

Production of conversion oxide-ceramic coatings on zirconium and titanium alloys

We consider the possibilities of surface hardening of zirconium and titanium alloys with conversion oxide-ceramic coatings. These coatings have been produced by the method of plasma-electrolytic treatment in alkaline solutions. We have established that the plasma temperature in discharge spark channels reaches (6–9) · 10³ K. The thickness of the coatings is 100 to 120 and 30 to 40 μm, and their microhardness is ∼ 800 and ∼ 1000 MPa for zirconium and titanium alloys, respectively. The functional properties of the coatings depend on the synthesis conditions, including the electrolyte composition, the cathode and anode current densities, and also the treatment time. We have evaluated the thickness, microhardness, and wear resistance of the coatings under conditions of dry friction and cavitation as well as their fatigue strength and corrosion resistance. We have established that this treatment provides a high wear and corrosion resistance of the alloys under study with insignificant decrease in their fatigue strength. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 42, No. 2, pp. 117–124, March–April, 2006.     

Development of oxidation resistant coatings for titanium alloys

Abstract

This work addresses the development of a coating to protect the titanium alloy designated IMI834 from oxidation and alpha case formation. This is to enable the safe use of the alloy at relatively high operating temperatures and thereby significantly improve the efficiency of aeroengines. Two different types of surface modification techniques have been employed to coat the titanium alloy: electrodeposition and pack aluminising. Cyclic isothermal oxidation studies revealed that platinum aluminide coating obtained by electrodeposition followed by pack aluminising exhibits good oxidation resistance compared with that exhibited by a plain aluminide coating. Based on results obtained by different techniques, it is suggested that platinum aluminide is a prospective coating material for preventing alpha case formation and protecting against oxidation in components fabricated from titanium alloy IMI834.     

Abrasive wear of plasma coatings with different structures on titanium alloys

We study the influence of plasma coatings having different structural and phase compositions on the serviceability of TS-5 titanium alloy under different kinds of abrasive wear. By means of X-ray phase analysis, we have detected significant changes in the composition of plasma coatings in comparison with the initial composition of the powders, interphase interaction between the components of these coatings, and the formation of complex coatings with nonidentified phases. We have corroborated that the intensity of abrasive wear under conditions of nonrigidly fastened abrasive particles is lower. The greatest changes in the test chart take place in the case of abrasive wear of the plasma coating POAN-30. The highest abrasive resistance is characteristic of a plasma coating with complex titanium and chromium carbide.Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 4, pp. 63–69, July–August, 2004.     

Deformation properties of amorphous alloys based on titanium

Translated from Fiziko-khimicehskay Mekhanika Materialov, Vol. 27, No. 3, pp. 77–79, May–June, 1991.     

Corrosion properties of titanium based hard coatings on steel

Titanium nitride TiN, titanium boronitride Ti(B,N) and titanium carbonitride Ti(C,N) coatings were deposited by PA-CVD on tempering and stainless steel substrates. The deposition process can be supervised by OES. The coatings were characterized XRD, SEM and WDS as well as hardness, adhesion and friction tests. Electrochemical impedance measurements and cyclic voltammetry in praxis relevant media were carried out. Mechanical and corrosion properties of the coatings can be controlled by the PA-CVD process parameters. The incorporation of chlorine in the coating can be varied by the process parameters with TiCl₄ or completely avoided using metallo-organic precursors. No influence of the chlorine content on the corrosion behavior was observed. Even coatings with extremely high chlorine content still exhibit an excellent corrosion resistance. Thus, the microstructure of the coating is the key to the corrosion properties of hard coatings on steel. A new micro electrochemical scanning droplet technique with a lateral resolution of 150 μm allows the investigation of TiN-coated substrates of complex geometry. The PA-CVD technique permits the deposition of dense and pinhole free coatings. On structures with simulated aspect ratios less than 3, a dense protective coating is proved. However, if the formation of micro pores is not suppressed by the optimal choice of deposition parameters, low-alloyed steel substrates corrode through pores, causing a detachment of the coating. On layers deposited on stainless steel, no sign of substrate corrosion could be detected. A model for the corrosion mechanism is given in Fig. 17.     

氮化钛薄膜光学性质的研究进展

介绍了拟合氮化钛薄膜光学常数常用的色散模型,且结合第一性原理计算出的能带结构和态密度给予阐述;概括了氮化钛在表面等离子体共振方面的研究进展和掺杂对于氮化钛薄膜光学性能的影响;并且指出了氮化钛在节能镀膜玻璃方面的应用。     

Physicochemical properties of electric-spark coatings based on VT6 titanium alloy

We establish regularities of the process of formation and physicomechanical and physicochemical properties of the surface of VT6 titanium alloy subjected to electric-spark alloying with electrode materials based on refractory compounds of titanium and zirconium. It is shown that, in the process of electricspark alloying, the maximum hardness and electrochemical resistance of the alloyed layer in natural corrosive environments are attained for materials based on carbide and titanium carbonitride and the highest resistance to high-temperature oxidation is attained for materials based on zirconium nitride and titanium carbonitride. Frantsevich Institute of Problems in Materials Science, Ukrainian Academy of Sciences, Kiev. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 32, No. 5, pp. 55–59, September–October, 1996.     

Tribological properties of carbonitride coatings formed on titanium by thermodiffusion carbonitriding

We have studied the tribological properties of VT14 titanium alloy with carbonitride coatings formed by the contact and noncontact method and binary (oxide and nitride) coatings. In the case of the contact method, specimens are saturated in a graphite backfill, and in the case of the noncontact method, specimens are located above it. We have investigated the wear resistance of a “titanium disk–bronze block” friction pair in AMH-10 hydraulic fluid under a load to 3 MPa on a friction path to 15 km. It has been established that coatings based on ternary interstitial compounds (titanium carbonitrides) provide a higher wear resistance than that of coatings based on binary interstitial compounds (titanium nitrides and oxides).     

镁合金超疏水环氧复合涂层的制备与性能EI北大核心CSCD

传统的超疏水表面的制备过程比较复杂,机械稳定性差,这严重制约了超疏水表面的实际应用。采用“黏合剂+纳米粒子”的方法,在镁合金表面制备一种无氟、持久稳定的超疏水环氧复合涂层。接触角测试结果表明,复合涂层的接触角最高可达160.2°,且在3.5%(质量分数)NaCl溶液中浸泡30天后,接触角仍然高达103°;EIS结果表明,在5个加速老化循环周期后,复合涂层的|Z|_(0.01 Hz)仍高于10^(9)Ω·cm^(2),展现出优异的耐盐雾性能和耐蚀性能;摩擦磨损实验结果显示,在19.6 N的载荷下机械摩擦8 h后,复合涂层的|Z|_(0.01 Hz)高达1.84×10^(9)Ω·cm^(2)。通过“空气垫”的屏障作用,复合涂层能够为镁合金提供高效且持久的腐蚀防护,“黏合剂+纳米粒子”策略为超疏水涂层的制备提供了新的思路。     

Elastic properties of two titanium alloys at low temperatures

Sound velocities and elastic constants were determined semi-continuously for two annealed polycrystalline titanium alloys between 4 and 300 K. Results are given for: longitudinal sound velocity, transverse sound velocity. Young's modulus, shear modulus, bulk modulus, Poisson's ratio, and elastic Debye temperature. A pulse-superposition technique was used.     

Effect of nitride coatings on corrosion and electrochemical properties of technical titanium

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 5, pp. 94–96, September–October, 1989.     

Effect of titanium on the structure and mechanical properties of Cu-Al-Ti alloys

The structure and mechanical properties of Cu10 wt% Al base alloys with 0–2.5 wt% Ti additions were investigated using transmission electron microscopy, optical microscopy and tensile tests. Addition of titanium has a decreasing effect on the grain size after quenching fromα + β region and causes significant strengthening of alloys. Alloy containing 1 wt%Ti quenched from 900° C shows mixture ofα, retainedβ (DO₃), disorderedβ′ (3R) and orderedβ′ ₁ (18R) martensites. Alloy with 2.5 wt% Ti addition after quenching containsα, retainedβ (DO₃), ordered T₁ phase of L2₁ superlattice and orderedβ′ ₁ martensite with either R18 or L1₀ structure indicating different stacking of ordered planes as the effect of titanium addition.     

The effect of microstructure on the mechanical properties of two-phase titanium alloys

This article presents the results of investigations of microstructure and mechanical properties of two-phase +β titanium alloys with different volume fraction of the β-phase. Microstructure of the specimens was examined using an optical microscope. Fracture surfaces were observed by SEM technique. The influence of the microstructure and phase composition on the mechanical properties of the alloys was studied. Static tensile tests, hardness tests and fatigue investigations were performed. It was noticed that the volume fraction and chemical composition of the β-phase has a significant effect on mechanical properties and cracking process during fatigue.