Showing papers in "Transactions of The Institute of Metal Finishing in 1983"
TL;DR: The scope of electroless nickel has been increased by codepositing materials such as silicon carbides, ceramics, diamonds and fluoropolymers as mentioned in this paper, which is achieved by taking advantage of different but complementary materials.
Abstract: The scope of electroless nickel has been increased by codepositing materials such as silicon carbides, ceramics, diamonds and fluoropolymers. This is achieved by taking advantage of different but o...
65 citations
TL;DR: In this paper, a novel process for the plating of decorative chromium from the trivalent state is described, and features of this new process include: colour of deposit virtually indistinguishable from that of conventional chromium.
Abstract: A novel process for the plating of decorative chromium from the trivalent state is described. Features of this new process include: colour of deposit virtually indistinguishable from that of conven...
36 citations
TL;DR: In this paper, the application of anodic currents during the first stage of chemical immersion phosphating has been studied in terms of potential-time behavior, coating weight development and coating porosity.
Abstract: SummaryThe application of anodic currents during the first stage of chemical immersion phosphating has been studied in terms of potential-time behavior, coating weight development and coating porosity. By use of a small current (0.5-2.0 mA cm−2) for short times (0.5-2.5 min) in an otherwise standard process cycle very high coating weights can be attained and the porosity of the final coating markedly improved.
20 citations
TL;DR: In this paper, the effects of heat treatment on the structure and corrosion resistance of a conventional electroless nickel deposit containing 8.4 wt% phosphorus and high integrity ENE alloy were investigated.
Abstract: SummaryEffects of heat treatment on the structure and corrosion resistance of a conventional electroless nickel deposit containing 8.4 wt% phosphorus and high integrity electroless nickel alloy con...
19 citations
TL;DR: In this paper, it is shown that the codeposition of inert particles in a metallic matrix involves two phenomena: the adsorption of ionic species on the inert particles and the adoration of inert particle on the c...
Abstract: Codeposition of inert particles in a metallic matrix involves two phenomena. Firstly, the adsorption of ionic species on the inert particles and secondly, the adsorption of inert particles on the c...
17 citations
TL;DR: In this paper, the wear process involved the formation of debris, its consolidation into a film and then cracking and exfoliation, and the wear rate at all thickness levels, 10, 25 and 40μm.
Abstract: SummaryFretting wear tests have been carried out on electroless coatings which have been plated onto low alloy steel substrates. A sphere on flat configuration was used for these experiments and the fretting amplitude was maintained at either 20 or 40 μm. Tests carried out in air at 20°C indicated that coatings containing 11–12% phosphorus in the as-deposited condition (500 HV) had lower wear rates than the underlying steel provided the coating thickness was >25μm. Heat treatment at 400°C, which raised the coating hardness to 1000HV, reduced the fretting wear rate at all thickness levels, 10, 25 and 40μm. Scanning electron microscope observations demonstrated that the wear process involved the formation of debris, its consolidation into a film and then cracking and exfoliation.Electroless nickel coatings in common with a number of coatings reduce the fatigue life of steel components by ~20%. The heat treatment of the coating to maximum hardness produces a further reduction in fatigue performance (~45%). T...
16 citations
TL;DR: In this paper, claims have been made by commercial platers of increasing nickel solution enrichment on changing from one form of nickel anode material to another, and to test these claims cathode and anode efficiency.
Abstract: Claims have been made by commercial platers of increasing nickel solution enrichment on changing from one form of nickel anode material to another. To test these claims cathode and anode efficiency...
12 citations
TL;DR: In this article, defects in the current understanding of electrolytic colouring are identified and considered in terms of film micro structure using electron microscopy and backscattered electron images obtained with the scanning electron microscope.
Abstract: SummaryDeficiencies in the current understanding of electrolytic colouring are identified and considered in terms of film micro structure. Electron optical methods suitable for microscopic study are described and it is indicated how each method has particular applications in elucidating mechanisms operative during colouring and explaining the properties of coloured finishes. Backscattered electron images obtained with the scanning electron microscope clearly reveal the deposit distribution in cross-section within the film. Major differences in distribution have been observed for different black finishes depending on the solution used for electrolytic colouring. Where deposits extend to or near the film surface, they act as preferential pathways for attack leading to premature failure during the acetic acid salt spray test. Transmission electron microscopy reveals the fine structural features of coloured films. Carbon replication and ultramicrotomy allow cross-sections to be studied in detail, while ion be...
8 citations
TL;DR: In this article, the P:P+H ratio was used as a unique indicator of corrosion performance, which is challenged and attention drawn to other experimental variables that may have significant influence, such as physical crystalline structure and porosity.
Abstract: SummarySystematically varied forms of zinc phosphated steel have been overpainted with a cathodic primer, a surfacer and a thermosetting acrylic top coat. The painted systems were then subjected to accelerated salt spray and exterior weathering tests. Their corrosion performance has been correlated with the P:P+H ratio, where P and H are the phosphophyllite and hopeite zinc phosphate levels respectively, determined by X-ray and electron diffraction techniques. Under the specific conditions chosen, two trends were discerned. Firstly, with the spray process, corrosion resistance increased with increase in P:P+H ratio. Secondly, with the spray/dip process, corrosion resistance decreased with increase in the P:P+H ratio. Thus unequivocal acceptance of this ratio as a unique indicator of corrosion performance is challenged and attention drawn to other experimental variables that may have significant influence, such as physical crystalline structure and porosity, etc.
7 citations
TL;DR: In this paper, a systematic study of electroforming solutions requires high solution conductivity and high metal ion concentration in order to fulfill their role as a rapid means of electroplating at minimum power cost.
Abstract: Electroforming solutions require high solution conductivity and high metal ion concentration in order to fulfil their role as a rapid means of electroplating at minimum power cost. A systematic stu...
5 citations
TL;DR: In this paper, various methods and processes suitable for the pretreatment of galvanized steel surfaces prior to the application of powder coatings, drawing upon results from industrial coating installations as well as those from laboratory testing, are discussed.
Abstract: SummaryThe paper covers the various methods and processes suitable for the pretreatment of galvanized steel surfaces prior to the application of powder coatings, drawing upon results from industrial coating installations as well as those from laboratory testing. It is important to differentiate between the types of zinc coated surfaces and in particular between strip-line galvanized steel sheet and heavy conventional hot dip galvanized steel. The main precleaning processes in use are alkali cleaning/etching and acid etching, the choice being influenced by the method of application and the thickness of the overlying zinc layer.Conversion coatings are necessary to ensure adequate service life and here the choice lies between chromating and phosphating. Accelerated corrosion tests have indicated that certain yellow Chromate processes are to be preferred for the treatment of thick galvanized surfaces, whereas Chromate, chromate/phosphate and micro-crystalline zinc phosphate processes may all be suitable for u...
TL;DR: In this article, a detailed study of the manufacture of Ag-sn and Ag-Sn-Cu powder deposits at rotating cylinder and vibrating cathodes was reported, where the electrolyte used was a cyanide-stannate bath.
Abstract: SummaryA detailed study of the manufacture of Ag-Sn and Ag-Sn-Cu powder deposits at rotating cylinder and vibrating cathodes is reported. The electrolyte used was a cyanide-stannate bath. The effects of cathode potential, mass transport (rotation rate of cylinder) and temperature were examined, as well as use of K+ in place of Na+ cations. It is shown that the silver deposition process is mass transport controlled, the tin activation controlled. There is no evidence to suggest that the various components of the bath interact with one another. The full range of Ag-Sn compositions can be formed as powders, and it appears that Cu in any proportion can be included in these powders. Powders having the composition of commercially available dental amalgam alloys (Ag-28% Sn, O-30% Cu) were prepared.
TL;DR: In this article, the authors present a paper on Throwing Power Measurement and its application in the context of the IMF: Vol. 61, No. 1, pp. 64-66.
Abstract: (1983). Notes on Throwing Power Measurement. Transactions of the IMF: Vol. 61, No. 1, pp. 64-66.
TL;DR: The solid state diffusion of copper and tin to produce intermetallic compounds at the interface between a coating of tin on copper or brass may be severely restricted by the use of a barrier layer of electroplated iron.
Abstract: SummaryThe solid state diffusion of copper and tin to produce intermetallic compounds at the interface between a coating of tin on copper or brass may be severely restricted by the use of a barrier layer of electroplated iron. Ultimately the barrier fails by rupturing due to the growth of copper/tin intermetallic compounds at pores in the iron layer.
TL;DR: In this article, a process for continuous plating of aluminium wire is described, where simple pretreatment steps in bifluoride-containing solutions, requiring very short immersion times ca 4-30 s, are employed, followed by electroplating from conventional copper, nickel or tin baths or combinations thereof.
Abstract: SummaryA process for the continuous plating of aluminium wire is described. Simple pretreatment steps in bifluoride-containing solutions, requiring very short immersion times ca 4–30 s, are employed, followed by electroplating from conventional copper, nickel or tin baths or combinations thereof. Several thousand metres of wire have been successfully processed. Adhesion of the plated coatings is very good, and contact resistance values of the plated wires are similar to those of pure copper.
TL;DR: In this article, a process for bright dipping copper and copper-based alloys in solutions containing sulphuric acid, hydrogen peroxide and a stabiliser which prevents the rapid spontaneous decomposition is described.
Abstract: The paper describes a process for bright dipping copper and copper-based alloys in solutions containing sulphuric acid, hydrogen peroxide and a stabiliser which prevents the rapid spontaneous decom...
TL;DR: In this paper, a stainless steel component undergo a series of mechanical, thermal and chemical treatments which affect their reaction rate on subsequent immersion in chromic/sulphuric acid colouring solutions.
Abstract: SummaryDuring manufacture, stainless steel components undergo a series of mechanical, thermal and chemical treatments which affect their reaction rate on subsequent immersion in chromic/sulphuric acid colouring solutions. Electropolishing slowed the overall colouring rate, whilst annealing and sensitising heat treatments decreased and increased the reactivity of the steel respectively. Colour uniformity was improved by electropolishing and more successfully by an anodic pretreatment in chromic acid.
TL;DR: The thickness of gold required to cover the color of the substrate has been determined and found to be 0.23 μm for a matt gold deposit on a substrate prepared to 600 grit as mentioned in this paper.
Abstract: The thickness of gold required to cover the colour of the substrate has been determined and found to be 0.23 μm for a matt gold deposit on a substrate prepared to 600 grit and 0.06 μm for a bright ...
TL;DR: The 15th Hothersall Memorial Lecture as discussed by the authors has been used as a platform for the IMF's annual meeting in 1983. But it has not yet been used in practice.
Abstract: (1983). Fifteenth Hothersall Memorial Lecture. Transactions of the IMF: Vol. 61, No. 1, pp. 126-130.
TL;DR: A number of considerations suggest that anodizing in molten salts might confer advantageous properties on the oxide film, such as improved corrosion-fatigue resistance, enhanced uniformity, better dielectric characteristics and superior adhesive bonding as discussed by the authors.
Abstract: SummaryA number of considerations suggest that anodizing in molten salts might confer advantageous properties on the oxide film. These include improved corrosion-fatigue resistance, enhanced uniformity, better dielectric characteristics and superior adhesive bonding. Most of these attractions are associated with the non-aqueous nature of the medium, molten salts representing the largest group of non-aqueous solvents. Although some early claims of improved films formed in melts are unproven, it is clear from the present programme that the structure of melt-anodized films can indeed be different from those grown in aqueous acid solutions. Futhermore, the presence (or absence) of dissolved water in the melt appears to play a crucial role in determining the type of film observed. During a continuing study, anodic films have been formed on aluminium, titanium, tungsten, niobium and molybdenum using mainly nitrate melts in the temperature range 45°-160°C. These have been characterised in various ways and some g...
TL;DR: Nickel and nickel-cobalt alloys were electroplated onto mild steel and then diffused into the surface layer of the steel by heating at 970°C or 1010°C for periods of up to 50 hours as discussed by the authors.
Abstract: Nickel and nickel-cobalt alloys were electroplated onto mild steel and then diffused into the surface layer of the steel by heating at 970°C or 1010°C for periods of up to 50 hours. The diffusion c...
TL;DR: An acid zinc plating process which uses a sodium chloride supporting electrolyte is now practical as discussed by the authors, and the acid depolarisation caused by the smaller sodium ion in the electric double layer can have a d
Abstract: An acid zinc plating process which uses a sodium chloride supporting electrolyte is now practical. Cathodic depolarisation caused by the smaller sodium ion in the electric double layer can have a d...
TL;DR: In this paper, the effect of coating alloy composition on the corrosion resistance and porosity of laboratory produced terneplate is assessed and the results indicate that an increase in the tin content of a coating...
Abstract: The effect of coating alloy composition on the corrosion resistance and porosity of laboratory produced terneplate is assessed. The results indicate that an increase in the tin content of a coating...