Surface Treatment of Stainless Steel

Benum, L.W. Wong, W. Oballa, M.C. Surface Treatment of Stainless Steel. Canadian Patent Application CA 2164021, Filed on November 29, 1995. 

Table 3.6. Effect of surface treatment of stainless steel on bond strength (EN58B steel-AV1566GB one component heat-cured epoxy (Ciba-Giegy))...

Virtanen, S., Ives, M, Sproule, G., Schmuki, R, Graham, M. (1997). A surface analytical and electrcxzhemical study on the role of cerium in the chemical surface treatment of stainless steels. Corrosion Science, Vol. 39, No. 10-11, pp. 1897-1913, ISSN 0010-938X... 

KMn04 include the surface treatment of carbon steels and stainless steels (descaling and desmutting), electrode coating of welding rods and decontamination of nuclear reactors (Reidies 2003). 

Roland, T, Retraint, D., Lu, K., Lu, J. (2006) Fatigue life improvement through surface nanostrucsuring of stainless steel by means of surface mecdianical attrition treatment. Scr. Mater., 54,1949-1954. 

There are various suggested systems for the pre-treatment of stainless steels which consist of treating the metal surface with strong acids to attack crystal grain boundaries in the... 

Any heat treatment of stainless steel should be preceded and followed by cleaning. Steel should be cleaned before heat treating to remove any foreign material that may be incorporated into the surface during the high-temperature exposure. Carbonaceous materials on the surface could result in an increase in the carbon content, causing carbide precipitation. Salts could cause excessive intergranular oxidation. Therefore, the stainless steel must be clean before it is heat treated. 

Although there is considerable evidence that chemical surface treatments improve the substrate bondability of stainless steels, there is no general agreement on which is the best. One etchant commonly used with stainless steels is an HNO3-HF mixture [128-131] others are chromic acid and ferric chloride/hydrochloric... 

The SBP membrane filtration system concentrates contaminants and reduces the volume of contaminated groundwater, surface water, storm water, landfill leachates, and industrial process water. This hyperfiltration system consists of stainless steel tubes coated with a multilayered membrane, which is formed in-place using proprietary chemicals. The membrane filtration system can be used with an SBP bioremediation system or another technology as part of a treatment train. 

Stainless steel 316L material used for piping and equipment shows considerable corrosion resistance because of the beneficial effect of molybdenum on the surface properties. It is also observed that the surface treatment (pre-reduced, polished, passivated and chemically treated surfaces) of stainless steel equipment and piping reduces the corrosion process in seawater applications. The corrosion resistance of stainless steel in seawater applications can also be enhanced by bulk alloying the stainless steel with nitrogen, chromium, molybdenum and nickel by converting the stainless steel into super austenitic stainless steel. From leaching studies it is also observed that the release of iron, chromium and nickel from the super austenitic stainless steel to seawater is considerably... 

In a cooling system where the water is saturated with oxygen, the primary rate-determining step is usually the rate of diffusion of dissolved oxygen at the cathode. Thus deaeration and the use of inhibitor treatments are ways of accomplishing cathodic polarization. Anodic polarization can also occur by the formation of a thin impervious oxide film, chemisorbed at the anode, such as takes place on the surface of stainless steels. However, for most metals used in cooling systems, the chemisorption process must be aided by anodic corrosion inhibitors. 

From the table above, it appears that aluminium oxide is extremely hard. That is why the material has to be processed with diamond. The compression, bending and tensile strengths of metals are dependent on the heat treatment. The modulus of elasticity of aluminium oxide is almost double that of stainless steel this means that twice the strength is needed for the same elastic deformation. Single crystals of aluminium oxide have been successfully used as implant material. They are made by adding the oxide powder to the surface of a seed crystal which is slowly withdrawn from an electric arc flame or oxygen/... 

Metallic Pigments. These pigments are metal flakes of various sizes made up of aluminum, copper, zinc, and/or their alloys. The aluminum flakes develop the silver metallic colors, whereas the copper, zinc, and aluminum alloys produce the gold, copper, brass, and bronze colors. The metal effect is modified, not only by shape and size, but also by perticle size distribution within a given product. Since aluminum, in particular, as a fine dry powder, can form explosive mixtures with air, most of these materials are commercially available in paste or liquid concentrates. In addition, surface treatments of these materials enhance their appearance and performance. Flakes of other metals, such as stainless steel, are used for surface protection purposes such as corrosion resistance and electrical conductivity. 

A reactor constructed of stainless steel 410 was used for pyrolysis since it contained no nickel. The coke layer formed during pyrolysis was usually thin and greyish. Less frequently, a piece of black coke was found on the surface. The metal surface (Surface C) was always grey. Figure 5 shows the two types of coke formed at Surface A in the stainless steel 410 reactor. The black (less frequent) coke appeared to be a floe of fine filaments, about 0.05 / m in diameter, with occasional 0.4- m filaments. The predominant deposit seems to be platelets of coke that include metal crystallite inclusions, the lighter area. The metal particles in the coke deposits, as detected by EDAX, were chromium rich compared with the bulk metal, as reported in Table III. Some sulfur also was present in the deposit the sulfur was present, no doubt, because of the prior treatment of the surface with hydrogen sulfide. Surfaces B and C for the stainless steel 410 reactor are also shown in Figure 6. Surface B indicated porous coke platelets. Surface C was covered mostly with coke platelets, and cavities existed on the surface. Metal crystallites rich in iron apparently were pulled from the metal surface and were now rather firmly bound to Surface B. Surface C was richer in chromium than the bulk metal. 

In the case of the direct electrochemical approach, while the electrolysis conditions are less severe, the selection of the appropriate electrode material is still very important, and further reading on the use of stainless steel [93], platinum [94], graphite [95], doped Sn02 [92], doped Pb02 [86, 87, 96], and so on, is suggested. The economic viability of the electrochemical treatment approach is influenced in no small way by the cost and lifetime of the anode material this can easily make or break the field implementation of the process. Some authors have used high-surface area, porous anodes for cyanide treatment in order to combat the problems of mass-transport limitations so evident at cyanide concentrations below 100 ppm [88]. That system consists of a reticulated vitreous carbon porous anode that was activated for cyanide oxidation by the deposition of some copper oxide. The process looks very promising at the laboratory scale,... 

Stainless steel is attacked, but it is possible to use plant constructed out of stainless steel made with a high molybdenum content provided certain precautions are taken. One safeguard is to passify the surface at intervals by filling the machine with a nitric acid solution of 10 to 20 per cent concentration, and treating at 50° to 60°C (122° to 140°F) for about 30 minutes, or alternatively, the addition of 8 to 12 oz of sodium nitrate per 100 gallons to every bleach is effective. Stainless steel lasts quite well if a chlorite bleach is followed by a peroxide treatment since the latter assists in the maintenance of the passive surface. Polarization of the stainless steel has been pro-... 

G.E. Coates, Effect of Some Surface Treatments on Corrosion of Stainless Steel, Mater. Perform., Vol 29 (No. 8), 1990, p 61-65... 

A number of other strategies have been investigated in order to improve the quality (selectivity and fluxes) or the synthesis efficiency of zeolite membranes by pre-treatment of the support. Most of these treatments are listed in [49], and include laser ablation, utilisation of diffusion barriers to limit sol infiltration, oxidation of stainless-steel supports, deposition of iron oxide to favour heterogeneous nucleation on the support and the use of acid attacks to activate the surface. 

Industrial applications of diffusion dialysis for acid recovery include recovery of acids from waste acid from surface treatment of steel and stainless steel, from alumilite treatment, from the etching process of aluminum and titanium, and in other hydrometallurgy industries. The recovery rate of acid can be controlled by changing the flow velocity of the waste solution and water in the dialyzer, in which solutions flow counter-current. For hydrochloric acid, as explained before,... 

Curing and aging of both epoxy systems is studied on two types of stainless steel. Substrate 1 (SSI) is a common stainless steel with 18% Cr and 8% Ni (Nirosta 4301). Substrate 2 (SS2) is a stainless steel containing 19% Cr, 7% Mn, and 3% Ni (Nirosta H400). SS2 performs excellently in crash tests. Both substrates possess rough surfaces due to the treatment by etching and blasting with steel beads (Rrms,ssi = 2.0 pm, Rrms,ss2 = 2.7 pm). 

The cost of various techniques can only be given very roughly, and any estimate will be incomplete, since the actual cost will vary from one application to another. Furthermore, different types of prevention mechanisms are not directly comparable. Beyond this, it can be said that with respect to normal carbon-steel reinforcement, use of galvanized and epoxy-coated bars costs about twice as much, and the cost of stainless-steel reinforcement is about 5 to 10 times higher. The use of nitrite inhibitors in higher doses costs approximately 30 /m of concrete (volume). Coatings may vary from 7 to 50 /m of concrete surface, hydrophobic treatment costs about 10 /m. Cathodic prevention varies from 50 to 100 /m. ... 

Although carburization can enhance the performance of certain components, in cases such as reformer tubes in the treatment of oil and hydrocarbons, carburization of stainless steels is deleterious and life limiting. In this case internal carbides form with kinetics analogous to those for internal oxidation." Consequently, alloys that are resistant to carburization are developed, primarily by alloying with nickel to reduce the diffusion coefficient of carbon, and with silicon and aluminium, which are thought to impart some protection by the formation of impervious silica and alumina surface hlms in the low-oxygen-potential atmospheres. ... 

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