Bronze surface preparation

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. 

Manual or power tool cleaning of an oxidized surface is sometimes the least thorough and slowest means of surface preparation. However, cost, location of the part, or the availability of tools often dictates the use of such a technique. Normally, only the top loose layers of rust on a piece of steel are removed through this method. Moisture and other contaminants remain in the residual scale. It is important to consider the compatibility of the tool with the substrate when using brushes or grinding wheels. For instance, the use of steel or bronze brushes to clean... 

It is true that good surface preparation is the key to successful adhesive bonding, but a few products have been developed that are oil tolerant. Loctite 603 for instance will retain oil-impregnated porous bronze bushes. 

In this work, hydrogen bronzes were prepared from M0O3 having retained a large surface area ( 30 m g l) after the standard treatment. 

The electrochemical replacement of one metal by another was noticed by Pliny in antiquity. He mentioned that iron looks like copper if it is smeared with vinegar or alum previously ground in a bronze mortar [275], Metal replacement seems to have also been used in the Roman era for tin-plating bronze, as well as underlying the recipes for the preparation of iron surfaces to receive amalgam gilding that are given in the 9th century [276],... 

Until now, little attention has been given to the analysis of ancient copper alloys with LA-ICP-MS. This type of material is usually analyzed with fast or instrumental neutron activation analysis (FNAA or INAA), particle induced X-ray emission (PIXE), X-ray fluorescence (XRF), inductively coupled plasma-atomic emission spectrometry or inductively coupled plasma-atomic absorption spectrometry (ICP-AES or ICP-AAS). Some of these techniques are destructive and involve extensive sample preparation, some measure only surface compositions, and some require access to a cyclotron or a reactor. LA-ICP-MS is riot affected by any of these inconveniences. We propose here an analytical protocol for copper alloys using LA-ICP-MS and present its application to the study of Matisse bronze sculptures. 

Reverse spillover or back-spillover is observed to proceed by surface migration of the spiltover species from the accepting sites to the metal, where it desorbs as H2 molecules or reacts with another hydrogen acceptor such as 02, pentene, ethylene, etc. Reverse or back-spillover (primary as well as secondary) is hindered by H20 (11), whereas secondary spillover is promoted by H20 (case B in Fig. 1). Hydrogen spillover depends on the acceptor surface it is thought to be easier on silica than on alumina (45) for hydrogen-molybdenum-bronze preparation. 

Metallic bronze fh(N 11, ), can, furthermore, be prepared from calcium-ammonia solution by evaporation of the ammonia. A bronze sohd is obtained, which in TH F at -30 °C behaves as a sohd surface in its reaction with alkyl hahdes (Scheme 4.17) [39]. Its apphcation in the reduction of 61 b produces a mixture of cyclopropane derivative 62 (81%) and straight-chain diphenylbutane 64 (8%). The process involves the formation of a tight anion radical-cation radical as an intermediate. Carbon-halogen bond cleavage occurs on the surface of the metalhc cluster. 

Alegria (Amaranthus h.) and alfalfa (Medicago s.) seeds were surface-sterilized 15 min in a 1% sodium hypochlorite solution and washed several times with water. The seeds were germined at 30 C in the dark for 3 days in a lattice of bronze inside of a special black acrilic cabinet. The etiolated shoots in each lattice were transferred to plastic boxes containing Hoagland solution with 0, 50, 100 or 200 mM NaCl and maintained 5 days in the dark (samples for mitochondria) orlight at 30 C, 4000 Lux and 12h photoperiod Preparation of mitochondria was performed as described by Bonner (6 ) ... 

Preparation of stable, zero-valent metallic copper solutions were demonstrated in either water or methanol [89]. After complexation within various surface modified poly(amidoamine) (PAMAM) dendrimers, copper(II) ions were reduced to zero valence metallic copper thus providing a bronze, transparent dendrimer-metal nanocomposite soluble in water. Solubility of the metal domains is determined by the surface properties of the dendrimer host molecules, however, their solutions still display characteristic optical properties associated with metal domains. Both aqueous and methanolic solutions of copper clusters were stable for several months in the absence of oxygen. Similar work and results were also reported by Crooks et al. [133]. 

In order to increase the adhesion [248] of polyethylene and polyvinyl butyral powders to steel, polystyrene is added to the first of these powders and chromium oxide to the second. The adhesion of powders prepared from polyamide resins to surfaces of aluminum and aluminum alloys or copper and copper alloys (brass, bronze) may be increased by introducing ultramarine and aluminum powders into the original material. 

Process control in today s highly automated production facilities is strongly dependent upon fast, precise and accurate chemical analysis, and XRF has been found to be widely applicable in the metal industries. XRF of metallic samples includes several solvable problems, especially in the areas of sample preparation and modelling calculations to convert intensities into concentration data. In general, metallic samples do not need complicated sample preparation, but the analytical information is derived from a volume close to the surface which must be polished. XRF is applied to various kinds of alloys, such as Na-Mg alloys, and Al, Ti, ferrous, Ni, Cu, Zr, W and Au alloys, bronzes... 

PREPARATION OF HIGH SURFACE AREA HYDROGEN MOLYBDENUM BRONZE CATALYSTS... 

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