Pre-treatment of copper

Anodic treatment may also be considered when bonding other metals. Examples inclnde the anodizing of magnesium in ammonium bifluoride solution, the anodic etching of stainless steel in nitric acid and anodizing of titanium in sodium hydroxide or chromic acid (see Pre-treatment of titanium). Alternative anodizing of copper can prodnce a Microflbrous surface (see Pre-treatment of copper). 

Needles of copper (II) oxide can be prepared on copper by oxidation of the metal at 90°C for 20 min in a solution of 3 g sodium chlorite, 10 g trisodium phosphate and 5 g L sodium hydroxide. The oxidized copper has a matt black appearance (see also Pre-treatment of copper). 

Detailed recipes for pre-treatment of copper, (which are also suitable for some copper alloys) are given in Refs. [1-4]. The simplest treatment consists of abrasion (see Abrasion treatment) with emery cloth followed by Degreasing in a chlorinated hydrocarbon solvent. Most of the treatments recommend a more elaborate routine of (1) degrease (2) etch and (3) dry. Etching solutions for use at ambient temperature include iron(III) chloride in either nitric or hydrochloric acid. Immersion for between 1 and 3 min is advised. Ammonium persulphate solution (1 3 or 1 4 parts by weight) is also used at room temperature perhaps for times as short as 30 s. ... 

Further detail may be found in articles on Pre-treatment of metals prior to painting, Pre-treatment of copper, Thermal spray processes and Rubber to metal bonding - pre-treatments. 

Pre-treatment of copper D E PACKHAM Conventional and microfibrous surfaces... 

Pre-treatment of the cathode produces a finely divided copper surface and this catalyses the hydrogenolysis of phenylhydroxylamine to aniline which becomes the principal reaction product. The reaction probably involves promotion of nitrogen-oxygen bond cleavage in the chemisorbed phenylhydroxylamine intermediate. 

Catalytic activity depends more on the nature and pre-treatment of the catalyst than on the content of copper. Thus, Cu(II)-exchanged KlO-montmorillonite displays an activity similar to the other clays and CuCl2-supported catalysts in spite of the very low amount of copper contained in that clay. Zeolite Y is less active than clays and does not promote the reaction at room temperature. Finally, calcination under dry air reduces the catalytic activity. 

In this work, it is shown that the copper-cerium oxide catalysts are active in the diesel soot combustion reaction. The isolated Cu ions seem to be the most active sites in such catalysts. The activity depends on the copper concentration and the pre-treatment of solids. Among all the tested catalysts, the lCulCe673 oxide, calcined at a relatively low temperature and containing the highest copper concentration, is the most active. 

In a previous investigation, we showed that feeding NO at low temperature (80°C) to Cu over-exchanged (640%) ZSM5 after He pre-treatment at elevated temperatures, a transient production of N2O is observed as result of catalyst re-oxidation [14]. Similar results have been obtained in the present study. Fig.3 shows that, after catalyst pre-treatment of 2 h in He flow at 550°C, causing copper ions reduction from Cu to Cu", the response to a step change of NO gaseous concentration (0-600 ppm) at 80°C, results in the transient formation of N2O due to the re-oxidation of copper sites. 

Careful surface preparation before adhesive application is essential for consistent and successful bonding to most substrates (see Pre-treatment of metals prior to bonding), and this certainly applies to copper, which has a reputation for being difficult to bond. Part of the difficulty is the friability of the black copper(ll) oxide, which forms on the surface in air at temperatures in the range 200-500 °C. At ambient temperatures, a thin layer of copper(I) oxide is present. 

A methanol-oxygen pre-treatment of the copper-catalysts at high temperatures is necessaiy to obtain catalytic oscillations in the copper/oxygen/methanol-system. For the pre-treatment the sample can be either treated with methanol-ojQrgen mixtures or alternating with oxygen and methanol at temperatures above 730 K. In a methanol-oxygen-helium flow (methanol to ojq gen ratio around 2 1, T > 730 K) the... 

We suppose that the indispensable high temperature pre-treatment of the copper sample generates a nanocrystalline copper bulk structure with dissolved oxygen. 

The painting procedure for other metal surfaces, although similar, the process of pre-treatment for cast iron components or non-ferrous metals, such as aluminium and copper, may need more care. The process of pre-treatment in such cases may vary slightly than for MS, as noted below. Such surfaces may require a change in the type of chemicals, their concentration and duration of treatment. The final surface preparation and painting procedure, however, will remain the same for all. 

Henriques, C., Ribiero, M., Abreu, C. el al. (1998) An FT-IR study of NO adsorption over Cu-exchanged MFI catalysts Effect of Si/Al ratio, copper loading and catalyst pre-treatment, Appl. Catal. B Environ., 16, 79. 

Aciylamide is required in very large quantities as the pre-polymer of the polyacrylamide that is very widely used in polymer and flocculant apphcations. The chemical manufacture of acrylamide has been estabhshed for a long time. The original process involved treatment of acrylonitrile with sulphuric acid at 90°C. More recently processes have been introduced that require the use of copper catalysts and high temperatures (80-140°C), but result in the formation of large quantities of toxic waste, including HCN. The expensive copper catalyst used is difficult to regenerate. In addition the chemical process produces aciylamide that requires considerable purification, for instance because the... 

Coating of polymer surfaces with thicker metal layers (10-30 pm) is a much more complicated operation. Several pre-treatment steps are required first the polymer surface has to be modified in such a way that, by a chemical process, a layer of copper or nickel can be deposited. With ABS use is made of the circumstance that it is a two-phase system, consisting of a hard matrix in which rubber particles are dispersed. The rubber particles present at the surface, are etched away, leaving a rough, porous surface, which offers a good adhesion to the chemically deposited copper or nickel. Thereafter the application by electrolysis of further layers of other metals (e.g. chromium) is simple. Also for PP, PMMA and polyamides, methods have been developed for chemical deposition of the first metal layer. 

It is thus necessary to optimise the effects of various pre-treatment chemicals, focusing on fabric physical properties such as tensile strength, weight loss, fuzzing, hand, copper number, moisture regain and colour change (in the case of dyed fabrics). 

The damages that occur during various pre-treatment processes of cellulosic fibres can be detected by various chemical tests like fluidity, copper number. Methylene Blue absorption and silver nitrate staining etc. 

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