Brass surface preparation

An advantage of metal-bonded grindstone (e.g. brass-bond cubic BN) is the possibility of electrolytic dressing (surface preparation). By applying voltage between the grindstone and an opposite electrode the metal bond can be... 

Brass is an alloy of copper and zinc, and bronze is an alloy of copper and tin. Sandblasting or other mechanical means of surface preparation may be used for both of these copper alloys. Surface treatment combining mechanical and chemical treatment with a solution of zinc oxide, sulfuric acid, and nitric acid is recommended for maximum adhesion properties. Adhesives similar to those recommended for copper may be used on brass and bronze substrates. 

Adhesives used with copper and copper alloys (see Section 6.2.5) can also be used with brass and bronze, although the surface preparation methods may be different. 

While it is possible to bond to a freshly abraded or cleaned metal surface, chemical treatments are preferred for rendering the metal surface inactive to corrosion over time. For low carbon steel, phosphatising is the recommended pre-bond surface preparation treatment. Stainless steel should be passivated or acid etched, while titanium is usually treated with a hydrofluoric acid pickle. Almninium or magnesium are best treated with a chromate conversion coating. Zinc and cadmium are generally prepared mechanically but a phosphate or chromic acid treatment may be used. Brass and copper may be treated with an ammonium persulphate etch or an acid-ferric chloride etch. 

The brass composition and also its surface composition are important, and adhesion is only obtained within rather narrow limits of copper percentages (roughly 65 -75%) and oxide film thickness. In other words, the surface preparation of the brass is very important. 

Brass is an alloy of copper and zinc. Sandblasting or other mechanical means of surface preparation may be used. The following procedure combines... 

It is hardly surprising that the preparation of surfaces of plain specimens for stress-corrosion tests can sometimes exert a marked influence upon results. Heat treatments carried out on specimens after their preparation is otherwise completed can produce barely perceptible changes in surface composition, e.g. decarburisation of steels or dezincification of brasses, that promote quite dramatic changes in stress-corrosion resistance. Similarly, oxide films, especially if formed at high temperatures during heat treatment or working, may influence results, especially through their effects upon the corrosion potential. 

Fourteen standard copper and brass alloys, the compositions of which have been certified by the National Bureau of Standards, have been used to calculate the concentrations of various elements in the coins (NBS C-1100. 1101, C-1102, 1106, C-1109, C-1111, C-1112, C-lllS, 1116, C-1120, 63C, 62D, 157A, and 158A). All standards were prepared metallographi-cally, ending with a diamond polish to obtain a surface representative of the interior of the standard. Excellent calibration curves were obtained with very good precision for both standards and coins, the calculated standard deviation is about 0.003% for Fe, 0.004% for Ni, 0.005% for Ag, 0.002% for Sn, 0.004% for Sb, and 0.003% for Pb. 

Cylindrical pellets of four industrial and laboratory prepared catalysts with mono- and bidisperse pore structure were tested. Selected pellets have different pore-size distribution with most frequent pore radii (rmax) in the range 8 - 2500 nm. Their textural properties were determined by mercury porosimetry and helium pycnometry (AutoPore III, AccuPyc 1330, Micromeritics, USA). Description, textural properties of catalysts pellets, diameters of (equivalent) spheres, 2R, (with the same volume to geometric surface ratio) and column void fractions, a, (calculated from the column volume and volume of packed pellets) are summarized in Table 1. Cylindrical brass pellets with the same height and diameter as porous catalysts were used as nonporous packing. 

Brass is certainly not an ideal material for this study. It would have been for better to use a polyisoprene grafted black such as prepared by LeBras and Papirer58 provided no other bonding sites were left available on the surface, and that it could be made certain that the bonded polymer could crosslink into the added rubber. 

The specimens are prepared by pouring the heated bitumen into ductility brass moulds assembled on a brass or metallic plate. Before pouring the bitumen, the surface of the metallic plate is coated with a release agent (typically a mixture of glycerin and talc powder). This prevents specimen from sticking to the plate and to the detachable middle part of the mould (side pieces), after allowing the filled mould to cool to room temperature. 

Brandt classed mercury, antimony, bismuth, cobalt, arsenic and zinc as semi-metals, rejecting cinnabar, vitriols, etc., from this class. He considered that true metals solidify from fusion with a convex surface. The semi-metals have a metallic appearance but are brittle under the hammer. He describes metallic zinc spiauter, conterfeth) from the East Indies, Rammelsberg, and Dalecarlia and Rattwick in Sweden, as a semi-metal. Blende is an ore of zinc and white vitriol is a compound of zinc, since it can be prepared by dissolving zinc in sulphuric acid, and if the solution of white vitriol is precipitated with alkali and the precipitate (zinc carbonate) heated with copper and charcoal, brass is produced. 

Each of the coins in both series was prepared only by wiping with a dry Kimwipe or a dry toothbrush to remove any loose soil or encrustation. In addition, coins were visually inspected to ensure that a clean surface could be exposed to the X-ray beam. No further physical or chemical modification of the coins surfaces was perfomied. After this cleaning and inspection, the coins were examined for Cu, Zn, Sn, Pb, Fe, Ni, As, Sb, Au, Pt, Pd, and Ag via energy dispersive X-ray fluorescence on a Kevex Spectrace Quanx instrument. Sample excitation conditions were as follows 20 kV, 0.10 mA, 100 second count, Ka,P for Fe, Ni, Cu, Zn, As, Pt, Au, and Pb, followed by 45 kV, 0.72 mA, 60 second count, L lines, for Pd, Ag, Sn, and Sb, using a rhodium target X-ray tube. Fundamental parameters software and pure element standards were utilized in detemining major and minor concentrations. Brass standards of known concentrations were run after each 100 samples, as a minimum. 

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