Packings surface treatment

P/M steels can be heat treated in the same manner as cast or wrought steels. They may be austenitized, quenched, and tempered. Surface hardening includes pack or gas carburization or nitriding, ie, heating in a nitrogen-containing atmosphere. Because of the greater amount of exposed surface area in the form of porosity, a protective atmosphere is needed (see Metal surface treatments). 

Corrosion of ammunition, weapons other items of ordnance is prevented by some type of treatment (such as painting, plating or other surface treatment) of many components, in addn to proper packing sealing to protect the components. The usual rust preventative lubricating oil preservative compds are not used on ammo components because they might prevent proper functioning, and also because ammo components contain many inaccesible cavities from which these materials cannot easily be removed (Ref 12a)... 

Reference to Table 7 will show the data for the two-pack polyurethane paint, and indicate a similar improvement to that of the epoxide paint due to the use of silanes. Although there are differences in the values for particular silanes on the different substrates and surface treatments, the general picture is that AAMS and MPS are the most effective in epoxide and polyurethane paints. 

Wetting For operation at low liquid loads, the onset of minimum wetting can adversely affect scale-up, particularly with random packings and aqueous systems. Scale-up reliability at low liquid loads can be improved by pilot-testing at the composition range expected in the prototype, and by using identical packing materials and surface treatment in the pilot tests and in the prototype. 

Experiments by Chuang and Miller (34) confirm good performance of 1 and 2 metallic, surface-treated CMR and 1 Hy-Pak at liquid rates of the order of 0.3 to 0.8 gpm/ft2 with an aqueous system. Their experiments also showed inferior performance when surface treatment was inadequate. This gives support to the metallic values listed in Table 8.6, but emphasizes that surface-treated and oxidized metal refer to proper conditioning of packing surfaces. 

To avoid packing variations, Jensen [31] and Losey et al. [126] formed regular posts within silicon channels as shown in Figure 17. These posts can be rendered catalytically active by surface treatment or, for example, by coating with alumina and subsequent impregnation with platinum [127],... 

Surface Treatment of the Wall Material or a Structured Packing... 

Polyethylene, as LDPE, LLDPE or a mixture or blend involving combinations of LDPE, MDPE, HDPE, EVA, etc., finds a wide usage in bags, sacks, sachets, overwraps, shrink wraps, stretch wraps, etc. Most deep freeze packs, for example, use LDPE or an LDPE mixture which is produced from a reel on a form fill seal type machine. However, as many of these packs are up to 100% printed, even ink of 2-5 Pm could be considered as a separate layer which modifies some of the physical and chemical properties. As all polyolefins need a surface (oxidative) treatment to ensure a good print key, this or any other surface treatment process may further modify the film properties. 

Choice of an appropiate surface treatment and a suitable primer are important because adhesion to the substrates presents difficulties [11.37]. Primers based on modified alkyd resins or two-pack epoxy-resins for derusted ferrous metals mainly contain zinc phosphate and zinc OKide as corrosion protection pigments. Nonferrous metals are first washed with an ammoniacal wetting agent before applying the primer that contains a binder based on synthetic resins (e.g., PVC copolymers, chlorinated rubber) which ensure good adhesion to the substrate. The same primer must be used on zinc or galvanized surfaces because the use of alkyd resins causes embrittlement [11.38] The primed surfaces are largely topcoated with alkyd resin systems. 

Reducing minimum wetdng rates. Surface treatment of the packing can... 

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