Cleaning and Surface Preparation

Spent cleaning solutions and rinse waters can contain all the metals plated or clad onto the boards. 

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Table 1.28 Prepainting cleaning and surface preparation processes...

The aim of cleaning and surface preparation operations is to eliminate as many deposits as possible in the systems (sludge, oil, soil, scale, etc.). This yields clean surfaces so that scale-forming and corrosion phenomena can be readily controlled by appropriate conditioning. 

Cleaning and surface preparation Spent acid/alkaline baths Waste rinse waters Metals, acids, alkalis... 

Application Methods and Surface Preparation. Eor good durabiHty and performance, proper surface preparation and correct appHcation of house paints are as important as the formulation of high quaHty paint. Proper surface preparation prior to painting involves several considerations. Eor new constmction, proper installation and protection of the substrate material are necessary. Eor previously painted surfaces, preparation involves mostly cleaning and removing any existing paint that is unstable. Once surface preparation is complete, the appHcation process can begin. 

Community pharmacies should be easily accessible to the public and maintained in a clean condition. Walls, floors, ceilings and windows must be kept clean and surfaces should be impervious and easily wiped. The premises should have a clear area set aside for the preparation and compounding of medicinal products and diagnostic testing, and all pharmaceutical or non-pharmaceutical waste and expired or deteriorated items should be segregated in a separate area. When the pharmacy is closed, the shop window may be totally closed off with aluminium shutters for security purposes. 

In his lecture Taylor emphasised both the phenomenological similarities and differences that existed between adsorption processes on technical catalysts and those observed with idealised catalysts produced by the Beeck evaporated film method to form oriented or non-oriented metal surfaces. These were inherent to the two schools of surface chemistry that had emerged, there were those who studied technical catalysts (Eucken, Emmett, Brunauer) and those who favoured the clean surface approach, where particular attention was given to vacuum conditions and surface preparation and exemplified by Beeck in Emeryville and Roberts in Cambridge. Kinetic studies were dominant with Trapnell, Tompkins and Kemball following the evaporated film approach in the 1950s and sixties. " ... 

Mori, S., Suginoya, M. and Tamai, I. (1982) Chemisorption of organic compounds on a clean aluminium surface prepared by cutting under high vacuum, ASLE Trans. 25 261-266. 

A ground system is only as good as the methods used to interconnect the component parts [9]. Do not use soldered-only connections outside the equipment building. Crimped/brazed and exothermic Cadwelded) connections are preferred. (Cadweld is a registered trademark of Erico Corp.) To make a proper bond, all metal surfaces must be cleaned, any finish removed to bare metal, and surface preparation compound applied. Protect all connections from moisture by appropriate means, usually sealing compound and heat-shrink tubing. 

Modified cyanoacrylates are now available which overcome the surface acidity and cure well on these surfaces (see Section 10.4.1). Acidic deposits may also be present as a result of an incorrect cleaning or surface preparation process. 

Fig. 15 Self-cleaning, antimicrobial surface prepared by utilizing PNIPAM and a quaternary ammonium salt. Reproduced with permission from Yu et al. [159]...

Surface preparation includes both cleaning and surface modification. Bombardment of the substrate surface by energetic particles prior to the deposition of the film material allows in situ cleaning of the surface (Sec. 13.11). Any surface placed in contact with a plasma will... 

Once a sample is properly oriented and polished, it is placed into a UHV chamber for the final preparation steps. Samples are processed in situ by a variety of methods in order to produce an atomically clean and flat surface. Ion bombardment and aimealing (IBA) is the most conunon method used. Other methods include cleaving and film growth. 

For example, energy transfer in molecule-surface collisions is best studied in nom-eactive systems, such as the scattering and trapping of rare-gas atoms or simple molecules at metal surfaces. We follow a similar approach below, discussing the dynamics of the different elementary processes separately. The surface must also be simplified compared to technologically relevant systems. To develop a detailed understanding, we must know exactly what the surface looks like and of what it is composed. This requires the use of surface science tools (section B 1.19-26) to prepare very well-characterized, atomically clean and ordered substrates on which reactions can be studied under ultrahigh vacuum conditions. The most accurate and specific experiments also employ molecular beam teclmiques, discussed in section B2.3. 

The substrate has to be prepared for cementation. The surface must be clean and free of oxide. Corners and edges are particularly important in diffusion-type coatings sharp edges are usually detrimental. Barrel finishing, ie, tumbling in a barrel with abrasive media, may result in the desired shape. 

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