A comparative study of titanium nitrides, TiN, TiNbN and TiCN, as coatings for biomedical applications

A strategy used to reduce wear of the ultra high molecular weight polyethylene (UHMWPE) component of orthopedic joint implants has been to coat the metallic part with a hard ceramic layer. The advantage of this procedure is to reduce both wear and ion release of the metal while keeping a high mechanical resistance. In the present study, the performance of three titanium nitride coatings: TiN, TiNbN, and TiCN for biomedical applications was assessed in terms of their surface properties and cytotoxicity. The morphology, chemical composition, and wettability were determined through atomic force microscopy (AFM) imaging, X-ray photoelectron spectroscopy (XPS) and contact angle measurement, respectively. The tribological behaviour of the coatings rubbing against UHMWPE in lubricated conditions was investigated using a pin-on-disk apparatus. Albumin adsorption on the three coatings was studied with a quartz crystal microbalance with dissipation (QCM-D) and AFM scratching. Cytotoxicity was determined both in direct or indirect contact of the cells with the coating materials. The results demonstrate that the three coatings have similar surface properties and are not cytotoxic. TiNbN seems to have the best tribological performance in the presence of albumin, although albumin adsorption is slightly higher on TiN.     

(Zr,Ti)CN coatings as potential candidates for biomedical applications

(Zr,Ti)CN hard coatings, deposited by DC magnetron sputtering on Ti6Al4V alloy and Si substrates, were investigated as possible candidates to be used as protective layers for medical implants. Two coating types, with different non-metal/metal ratios, were prepared. The films were analyzed for elemental and phase composition, crystallographic structure, mechanical properties, corrosion behavior, surface wettability and cell viability. The coatings were found to have composite structures, in which a (Zr,Ti)CN crystalline phase coexists with an amorphous a-C(N) one. Film thickness and hardness in the ranges 1.8-2.1 μm and 25-29 GPa, respectively, were measured. The coated samples exhibited an improved corrosion resistance as compared with the Ti6Al4V alloy. Both coating types were found to be hydrophobic, the contact angles being higher than 100°. Cell viability measurements proved that the osteosarcoma cells are adherent to the coating surface, the highest viability (90.5%) after one week incubation being found for the film with high non-metal content.     

Bulk-surface hardening as a method for increasing strength,reliability, and service life of machine parts

In the last 20–30 years the efforts of researchers and technologists have been directed at finding ways for practical realization of the high-strength state of steel. The results were mainly used for parts of special equipment, namely, spacecraft, aircraft, and submarines. However, it is no less important to realize the high-strength state in parts of conventional machines, where the consumption of metal is very high, and the utilization of this state will substantially reduce the mass of machines and mechanisms, improve their operating parameters. and decrease their cost. The article is devoted to bulk-surface hardening as a method of efficient strengthening of machine parts.Translated from Metaliovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 2–9, November, 1995.TEKHMASH Research and Production Association.     

Electrodeposits as Bases for Paints

Two proprietary bright nickel solutions were operated under simulated production conditions, properties of the deposits and of the solutions being measured periodically. No particular difficulty was experienced in operating each bath for about 1200 Ah/gal, after which the solutions began to produce unacceptable deposits.

Important properties affected by ageing of the solution were brightness, internal stress and ductility. Stress tended to increase and ductility to decrease. The brightness range of one solution contracted with time, and the solution was deemed to require purifying when it became impossible to maintain brightness all over the plated articles. Purification of the other solution was considered to be necessary when the deposit became excessively brittle. Drag-out and other solution losses were small; had they been larger, the solutions would probably have produced satisfactory plate for a longer period, for reasons discussed in the paper.

Many properties were unaffected by ageing, e.g. throwing power, microhardness, adhesion. It was also found that the accuracy of two methods of determining nickel thickness—B.N.F. jet test and thermoelectric method—was unrelated to the length of service of the plating bath.

The changes in properties appear to be due to organic impurities in the solution, arising more probably from decomposition of addition agents than from external sources. Consideration of the factors determining the concentration of impurities suggests that it would be more economical in practice to maintain a tolerated level of impurity than to remove all the impurity periodically.     

Suppressing sulfate-reducing bacteria, as well as hydrogen diffusion through steel, by inhibitors of AMDOR IC type

Suppressing both the vital activity of sulfate-reducing bacteria and hydrogen diffusion through a steel membrane by AMDOR IC inhibitors is studied at a free-corrosion potential, as well as cathodic and anodic polarization, of the membrane working surface. Original Russian Text ? V.I. Vigdorovich, M.V. Vigdorovich, A.V. Ryazanov, A.N. Zavershinskii, 2007, published in Zashchita Metallov, 2007, Vol. 43, No. 1, pp. 103–107.     

SiO_2、ZrO_2作为填料的牙科可切削聚合物基复合材料的制备

采用纳米SiO_2和ZrO_2复合粉体作为填料,PMMA为树脂基质制备复合材料.介绍了复合材料的制备工艺.并对材料进行差热分析及XRD、SEM微观分析.结果表明:SiO_2在复合树脂中主要起增强作用,而ZrO_2在复合树脂中起提高耐磨性的作用.从制备工艺和外观上看,30%纳米SiO_2和10%~20%ZrO_2复合增强PMMA是比较成功的.     

铸铁中用氧化钼代替钼铁的热力学分析

分析了铁液中硅、碳等元素将氧化钼（ＭｏＯ３）中的钼还原出来的热力学、动力学以及铁液的质量。指出：在含钼量小于１％时,采用浇包内加氧化钼的方法,钼的吸收率达９５％以上,用氧化钼代替钼铁,不仅能保证铁液的质量,还能降低铸铁件的成本。     

NiCrM (M = W, Mo, V) ternary alloy tapes as cube-textured substrates for second-generation superconducting cables

Development of the deformation texture and recrystallization processes have been studied in some ternary nickel-based alloys of the Ni-Cr-W, Ni-Cr-Mo, and Ni-Cr-V systems. An optimum relationship between the amounts of the alloying elements upon the combined alloying of nickel has been found. Problems of the optimization of the regimes of recrystallization annealing have been considered, which are related to an increase in the temperature of the onset of primary recrystallization in ternary nickel alloys after deformation by rolling to large reductions. An analysis of mechanical and magnetic properties of all the alloys has been performed.     

Expert system shell for welding preheating: Technical and economic problems,as well as its impact on the physical environment ‐ part 3

Summary

This article, published in three parts, is based on a doctoral thesis undertaken at the Department of Applied Mechanics and Engine Construction of Genoa University, in collaboration with the Italian Welding Institute. The aim of this article is to study the thermological, metallurgical, economic and safety problems of preheating which arise in fusion welding of steels and to acquire a basic knowledge of these phenomena, as fully and logically as possible. On this basis, a simple, flexible and expandable tool, illustrated by experiments, has been devised for use by expert welding engineers.

For this purpose, state‐of‐the‐art research, national and international standards were studied, and experimental tests conducted to correlate available data.

An expert system (ES) was thus produced, using artificial intelligence techniques, in order to determine preheat temperature, evaluate costs, and make health and safety recommendations to the user.

In this third part, the development of the expert shell is described, as well as a brief software user's guide.     

Fly Ash Permeability During Liquid AA7075 Infiltration, as a Reutilization Method for Novel MMCs

The reutilization of waste materials into novel products is widely recognized as a challenge of high technologic interest. This investigation aims to sustain fly ash as a suitable ceramic preform for the production of MMCs by liquid metal infiltration of a high-alloyed aluminum (AA7075). The effect of a series of production parameters on the resulting microstructural homogeneity of the MMC is quantified. The influence of binder concentration preform dimension and orientation are evaluated among others. Starting materials, preform, and final product are examined by optical microscopy, SEM, EDX, and XRD indicating the developing structures and dominating phenomena throughout the manufacturing process.     

Amines as Corrosion Inhibitors for Copper

The study of the inhibiting effect of certain pyridine and aniline derivatives on the corrosion of copper in persulphate solutions enables the compounds to be arranged in the following series of decreasing inhibiting power; 2,6-lutidine – 2-picoline – pyridine – m-anisidine – p-phenetidine – aniline. Inhibition may generally be attributed to the adsorption of organic molecules, nitrogen being an electron donor and becoming attached to the metal surface. Symmetric substitution by methyl groups in the pyridine molecule increases the inhibiting effect. In the case of aniline derivatives m-anisidine is superior to the other compounds studied. On the base of electrochemical experiments it may be concluded that the reaction is under cathodic control, the cathode being extremely polarized at high current densities.     

用金作保护剂铅试金富集汽车尾气净化催化剂中铂钯铑的研究

建立了用金作保护剂,铅试金一步富集汽车尾气净化催化剂中铂钯铑的方法。研究了金保护剂的条件,对比了不同方法的富集效果。结果表明:加入20～40 mg金作保护剂,试金配料硅酸度为1.0,进炉温度900℃1,130℃恒温10 min,熔炼时间50～60 min,灰吹温度910℃,可完全富集500μg铂钯铑。方法富集效果好,操作简便,适用于汽车尾气净化催化剂、熔炼渣以及日常样品中0.x～xxxx g/t铂钯铑的分析。     

The Water-Soluble Peripheral Substituted Phthalocyanines as Corrosion Inhibitors for Copper in 0.1 N HCl: Gravimetric,Electrochemical, SEM-EDS,and Quantum Chemical Calculations

Protection of Metals and Physical Chemistry of Surfaces - Corrosion inhibition effects of water-soluble peripheral substituted cobalt, copper and zinc metallophthalocyanines (CoPc (1), CuPc (2) and...     

Expert system shell for welding preheating: Technical and economic problems,as well as its impact on the physical environment (Part 2)

Summary

This article, published in three parts, is based on a doctoral thesis undertaken at the Department of Applied Mechanics and Engine Construction of Genoa University in collaboration with the Italian Institute of Welding. The aim of this article is to study the thermological, metallurgical, economic and safety problems of preheating which arise in fusion welding of steels and to acquire a basic knowledge of these phenomena as fully and logically as possible. On this basis, a simple, flexible and expandable tool, illustrated by experiments, has been devised for use by expert welding engineers.

For this purpose, state‐of‐the‐art research, national and international standards were studied and experimental tests conducted to correlate available data.

An expert system was thus produced, using artificial intelligence techniques, in order to determine preheating temperature, evaluate costs, and make health and safety recommendations to the user. This second section considers the issues of economics, safety and the environment.     

Nano-SnO_2 Decorated Carbon Cloth as Flexible,Self-supporting and Additive-Free Anode for Sodium/Lithium-Ion Batteries

In this study,nano-sized SnO_2 decorated on carbon cloth(SnO_2/CC) is prepared through a simple and facile solid method.The nano-sized SnO_2 is uniformly distributed on the surface of carbon fibers in carbon cloth,providing sufficient free space to relieve volume expansion and reduce electrode pulverization during cycling.The as-prepared SnO_2/CC as a flexible,self-supporting and additive-free anode electrode for sodium-ion/lithium-ion batteries(SIBs/LIBs) can demonstrate outstanding electrochemical performance.SnO_2/CC after annealing at 350℃(SC-350) as an anode for SIBs can deliver a reversible capacity of 0.587 mA h cm~(-2) at the current density of 0.3 mA cm~(-2) after 100 cycles.In addition,when cycling at 1.5 mA cm~(-2),SC-350 can maintain 1.69 mA h cm~(-2) after 500 cycles when used as LIB anode.These results illustrate that the as-prepared SnO_2/CC can be a promising flexible anode material for flexible SIBs/LIBs and provide a simple and practical method for designing new flexible electrode materials.