Dynamic thermal tomography: Recent improvements and applications

The concept of “dynamic thermal tomography” (DTT) was suggested in the 1980s. At that time, there was a wave of interest in the tomographic analysis of materials by active thermal nondestructive testing (TNDT). Unlike particles and quanta of electromagnetic radiation, thermal energy propagates in solids by diffusion. Therefore, a purely geometrical approach, that is characteristic of computed X-ray tomography, is replaced in DTT with the analysis of the evolution of temperature versus time. DTT is based on the fact that, in one-sided TNDT, deeper material layers are characterized by longer time delays of the thermal response. The DTT algorithm is relatively stable when used in the inspection of certain materials. Thermal waves experience damping by amplitude and retardation in time. This limits the detection depth and produces certain artifacts that can be suppressed by thresholding maxigrams. DTT can also be considered as a specific way of data presentation that has proven to be useful in many practical cases, including surface and volumetric thermal stimulation of both metals and non-metals. Thermal tomograms appear similar to binary maps of defects, thus enabling more reliable defect detection in comparison to conventional IR thermograms. In this paper, a “reference-free” approach to DTT is proposed being based on some mathematical manipulations with a front-surface temperature response. Also, the possibility of using the DTT principles for processing the results of ultrasonic infrared thermography is demonstrated.     

Matrix factorization methods: Application to thermal NDT/E

A typical problem in thermal nondestructive testing/evaluation (TNDT/E) is that of unsupervised feature extraction from the experimental data. Matrix factorization methods (MFMs) are mathematical techniques well suited for this task. In this paper we present the application of three MFMs: principal component analysis (PCA), non-negative matrix factorization (NMF), and archetypal analysis (AA). To better understand the peculiarities of each method the results are first compared on simulated data. It will be shown that the shape of the data set strongly affects the performance. A good understanding of the actual shape of the thermal NDT data is required to properly choose the most suitable MFM, as it is shown in the application to experimental data.     

Electrochemical behavior and corrosion of iron in aqueous sulfidic solution

This paper discusses the electrochemical behavior and corrosivity of aqueous sulfidic solutions with reference to iron and carbon steel. The chemistry of aqueous sulfidic solutions is reviewed with particular emphasis on stability of various sulfur species in aqueous solutions as a function of pH and solution potential. The thermodynamic predictions of corrosion processes for iron in sulfidic solution are discussed in terms of the potential pH equilibrium diagrams. Considerable discussion of the corrosion and electrochemical behavior of iron in sulfidic solutions includes the role of solution composition on corrosion and polarization behavior. The influence of surface films on corrosion in these systems is also discussed. The paper concludes with a discussion of the role solution composition on hydrogen absorption and embrittlement of iron and carbon steel.     

Effect of Metal Finishing Wastes on Sewage Purification

The through-hole plating of printed circuits is essentially a method of electroplating non-conductors, and can be divided into four basic sections—cleaning, activation, metallization and electroplating. Activation consists of the absorption of tin compounds and a precious metal from either two separate solutions or one single solution; a comparison is drawn between these two methods indicating the advantages to be gained from the single stage solution. Electroless copper solutions are generally used for metallization and the working parameters of these are considered. Build up of the electroless film is carried out in copper electroplating solutions of which several types are available. A comparison is drawn between these solutions, with respect to throwing power, stability and grain structure of the deposit. Other electroplating systems used to deposit etch resists and solderable surfaces are also discussed.     

Wasserstoffinduzierte Spannungsrißkorrosion an unverzinkten und verzinkten Baustählen

Hydrogen induced stress corrosion cracking of non galvanized and galvanized construction steels The processes of atmospheric corrosion and corrosion in collected water which may lead to hydrogen induced stress corrosion cracking of high-strength reinforcing steels in casing tubes before injection with concrete are discussed. Hydrogen uptake during corrosion occurs in weakly acid solutions as well as in neutral or alkaline aqueous solutions. The hydrogen uptake by proton discharge in acid solutions decreases with increasing pH of the electrolyte. Hydrogen can also be absorbed in neutral to weakly alkaline solutions if steels are plastically deformed and water reacts with the fresh iron surface. In alkaline solutions, hydrogen uptake is possible if, at the generally passivated steel surface, localized corrosion (pitting or crevice corrosion), local galvanic cells and a sufficient decrease in the pH of the pit electrolyte occurs. In the case of galvanized steels with damaged zinc layers, hydrogen uptake may result from the cathodic polarization of the free steel surface by zinc dissolution. The absorbed hydrogen interacts with the microstructure of the steels and weakens the bonds between the iron atoms. The influence of the microstructure of high-strength steels on the fracture behaviour is discussed on the basic of the so-called decohesion theory.     

The compound energy model for ionic solutions with applications to solid oxides

The application of the compound energy model to crystalline ionic phases is discussed and compared with the regular solution model. Its application to solutions with reciprocal reactions between cations on different sublattices is discussed with special reference to oxides. Examples are taken from various solutions between spinels, including cases with vacancies and interstitials. Problems connected with the choice of a state of reference for charged components in a multicomponent solution are addressed. This paper was presented at the International Phase Diagram Prediction Symposium sponsored by the ASM/MSD Thermodynamics and Phase Equilibria Committee at Materials Week, October21-23,1991, in Cincinnati, Ohio. The symposium was organized by John Morral, University of Connecticut, and Philip Nash, Illinois Institute of Technology.     

The compound energy model for ionic solutions with applications to solid oxides

The application of the compound energy model to crystalline ionic phases is discussed and compared with the regular solution model. Its application to solutions with reciprocal reactions between cations on different sublattices is discussed with special reference to oxides. Examples are taken from various solutions between spinels, including cases with vacancies and interstitials. Problems connected with the choice of a state of reference for charged components in a multicomponent solution are addressed. This paper was presented at the International Phase Diagram Prediction Symposium sponsored by the ASM/MSD Thermodynamics and Phase Equilibria Committee at Materials Week, October21-23,1991, in Cincinnati, Ohio. The symposium was organized by John Morral, University of Connecticut, and Philip Nash, Illinois Institute of Technology.     

Zinkphosphat-Überzüge aus übersättigten Bädern

Zinc phosphate coatings from supersaturated baths The author studied the properties of supersaturated phosphating solutions containing zinc phosphate being used for phosphating steel. The study included the influence of the solution variables, and in particular of the ferrous ion concentration, on the supersaturation and the coating properties. The accelerating effect of supersaturation is so strong that heavy, dense, and fine grain coatings are obtained without oxidants and at temperatures as low as + 10° C. Some aspects of the kinetics and the mechanism of coating formation in supersaturated solutions are discussed. Supersaturated phosphating solutions with zinc phosphate may find practical application, particularly where a high degree of protection is desired.     

Features of adsorption of globular proteins by nanoporous silica

The adsorption of globular protein macromolecules, bovine serum albumin, and gamma globulin from aqueous solutions at 293 K by nanoporous silica sorbents is investigated. The dependences of the maximum value of adsorption of albumin and gamma globulin from aqueous solutions on the size of nanopores of silica sorbent are obtained. Based on this dependence, the sizes of macromolecular protein structures formed during the adsorption process are determined. A method for evaluating the thickness of adsorbed layers of protein macromolecules on silica surface is proposed. The behavior features of globular proteins in silica nanopores are discussed.     

Highlights from the IMF AGM,Birmingham, December 2014

Abstract

Measurements of solution conductivity are reported for chromic acid solutions typical of those used in chromium electroplating. Optimum concentrations for conductivity are noted (450 g L^?1) and the temperature ranges of ion dominance have been discussed including the use of ion colours in solution. It is concluded that practical solutions normally have trichromate and tetrachromate ions as dominant species.     

Electrochemical equilibria of cadmium and water and the dissolution of cadmium as a function of pH

The dissolution of Cd in solutions of pH 1–15 has been determined. The corrosion behaviour follows the theoretical predictions of corrosion and passivity. In particular, substantial corrosion was observed in a small range of the highly alkaline solutions. The results are discussed.     

级进冲裁中跳屑现象的原因与解决方法

针对连接器端子类零件在级进冲裁中的跳屑现象进行了研究和原因分析,讨论了其对生产造成的不良影响,并提出了在实践中总结出的有效解决方法.     

镁合金化学转化膜

综述了镁合金化学转化膜技术的现状，主要涉及化学转化处理工艺及在多种不同处理液中所得到的转化膜的特性，最后还展望了今后镁合金化学转化膜的发展趋势。     

Influence of some anions on the stress corrosion of low alloy steels in aqueous solutions

Polarization and stress corrosion behaviour of two types of low alloy steels, AISI 4130X and AISI 4145, were studied in agitated 0.05 M sodium acetate and 0.05 M trisodium phosphate solutions saturated with natural gas at room temperature. The magnitude of currents, shown in potentiokinetic polarization curves in the range of —0.8 V(SCE) to +0.8 V(SCE) in these media, is very small compared with earlier results obtained in sulphate and chloride solutions.Stress corrosion experiments conducted using a slow strain rate technique under cathodic conditions indicate the onset of hydrogen embrittlement on both types of steel in sulphate, chloride, acetate and phosphate solutions. Under anodic conditions, the results in 0.05 M sodium acetate solutions indicate strong susceptibility to stress corrosion compared with no susceptibility in 0.05 M trisodium phosphate solutions if there is no onset of pitting. These results are in contrast with results showing strong anodic dissolution and consequent absence of stress corrosion under anodic conditions in sulphate and chloride media.Results of Auger and IR analyses of anodic surface films formed in acetate and phosphate solutions are presented and discussed in relation to their observed mechanical behaviour.     

Finely grained nanometric and submicrometric coatings by thermal spraying: A review

Technology, microstructure and properties of nanostructured coatings obtained using different feedstock including: (i) powders composed of agglomerated nanocrystals; (ii) solutions; and (iii) suspensions are discussed. The methods of nanostructured coarse powders manufacturing are reviewed together with the problems related to formulation of solutions and suspensions. A particular attention is paid to the key problem at liquid feedstock spraying, namely to their delivery and injection into jets or flames. The physical and chemical phenomena occurring at flight of injected liquid droplet of solution and suspension are shown and related to the formation of coatings and their microstructure. Some microstructural, chemical, mechanical and electrical properties of coatings are collected and related to the operational processing parameters by regression equations derived from the design of spray experiments. Finally, the possible applications of nanostructured coatings are briefly discussed.     

宝钢2050热轧除鳞装置的改造

介绍了宝钢２０５０热轧除鳞装置存在的问题及解决方法。     

Mo在水溶液中的耐腐蚀性能

综述了Mo在不同溶液中的电化学行为、电池作用腐蚀 行为，并从技术的角度总结了它在各种碱性溶液、酸性溶液、无机盐溶液以及海水中的耐蚀性能.最后对研究工作进行了展望.     

ERW直缝焊管内毛刺清除装置的发展

简述了ERW直缝焊管清除内毛刺的方法及设备构成;重点介绍了内毛刺清除装置尤其是刀架的发展进程,在使用过程中经常会发生的问题及消除方法;同时还指出了未来发展方向。     

Au Recovery Using an Activated Carbon Column

The feasibility of a process involving the use of activated carbon in a multistage column (NIMCIX contactor) for the recovery of gold from unclarified pregnant solutions was investigated on pilot-plant scale. It was found that satisfactory extractions, corresponding to a recovery of 99.6 percent, can be achieved with an average gold concentration of 0.0077 p.p.m. in the barren solutions from a feed averaging 1.89 p.p.m. The results show that excessive loading of CaCO₃ can be prevented by lowering of the pH of the feed to about 7.6. This obviates the need for the carbon to be treated with hydrochloric acid. The gold was eluted from the carbon by the Zadra procedure. The operating conditions of the elution and electrowinning circuits are reported, and the elution of the gold and other metals is discussed. The reactivation of the carbon, which was carried out in a vibrating-deck kiln, is described, and the effects of this reactivation on the activity of the carbon and its microstructure are also discussed. The consumption of reagents in the adsorption and elution circuits is presented in sufficient detail to allow the potential of the activated-carbon process as an alternative to the Merrill-Crowe process for the treatment of high-grade solutions to be evaluated. In addition, the results of parallel small-scale investigations on the effect of pH on the loading of CaCO₃, gold, and other metals on activated carbon are presented and discussed briefly.