Steels silanes bonded

FIGURE 10.3 Effect of silane adhesion promoter on the durability of a mild steel joint bonded with epoxy adhesives.16... 

Fig. 1. SSIMS spectrum showing evidence of Fe-O-Si and Cr-O-Si bonding at a silane/steel interface (from Ref. 29 ).

In primer formulations for adhesive bonding of metals, the coupling agents that are most frequently used are those based on epoxy and amine functionalities. Aqueous solutions of aminosilanes have been successfully used for obtaining stable adhesive bonds between epoxy and steel [10] and epoxy and titanium [11,12], while epoxy functional silanes are preferable for applications involving aluminum substrates [13,14], A simple solution of % epoxy functional silane in water is currently used for field repairs of military aircraft [15] where phosphoric acid anodization would be extremely difficult to carry out, and performance is deemed quite acceptable. 

As discussed above, silane primers have been investigated extensively for adhesive bonding of steel substrates and have been shown to be quite effective, but the extent to which these are in current commercial use is not known. 

Abstract— The use of organosilanes as adhesion promoters for surface coatings, adhesives and syntactic foams is described and reviewed in the light of published work. Data are presented on the beneficial effect of silanes, when used as pretreatment primers and additives, on the bond strength of two pack epoxide and polyurethane paints applied to aluminium and mild steel. It is shown that silanes when used as additives to structural epoxide and polyurethane adhesives are less effective than when used as pretreatment primers on metals but are highly effective on glass substrates. The compressive properties of glass microballoon/epoxide syntactic foams are shown to be markedly improved by the addition of silanes. 

The effect of using different silanes as pretreatment primers on the initial bond strength of a two pack polyamide cured epoxide to mild steel and aluminium is shown in Table 2. 

It seems less likely that MAMS is reactive towards either epoxide or isocyanate groups. In spite of this MAMS performed well, in some cases, notably the polyurethane paint on mild steel and aluminium, see Tables 3 and 7, better than ECMS and APES. Clearly chemical reaction is not a prerequisite for bond strength enhancement. Chain tangling, simple physical effects, may play an important role with both MPS and MAMS and possibly other silanes. 

Static SIMS would be particularly appropriate to study films formed by silane coupling agents by virtue of its high surface sensitivity, its capability to detect all elements and isotopes, and because it provides molecular structural information on organic materials [9-12], So far, SIMS has rarely been used to study silane films. It was used, however, to detect covalent bonds between iron or chromium and silane films deposited on stainless steel [13, 14], Such bonds were indeed reported this claim was based on the presence of ions in the spectrum which were assumed to be FeOSi+ and CrOSi. However, these SIMS analyses were not done under static conditions, which had not yet been established at the time of these studies. 

It should further be noted that the Fe—O—Si+ ion at +100 amu, which was reported in the literature as evidence for covalent bond formation [13], is not observed here. The low intensity of the ions at 56 amu (56Fe+) and the detection of iron-containing ions in the spectrum are consistent with an etching of the steel substrate by the silane solution. Such attack of metallic substrates has been reported for Zn and A1 [3], but not yet for steel. 

The bonding environments surroundir alkyl. Si—CH3, Si—CH2, Si—H, and Si ing is believed to be a typical oxane I sitions of deposited silane plasma pob C/Si and O/ Si atomic ratios increas Organofunctional silane polymer coati silane polymers. Corrosion performar to be excellent. The results were partic silane polymer and organofunctiona phosphated steel substrates. 

Procedure (See Chromatography, Appendix IIA.) Use a high-performance liquid chromatograph equipped with an ultraviolet detector that measures absorption at 254 nm and a 25- to 30-cm x 4-mm (id) stainless-steel column, or equivalent, packed with octadecyl silane chemically bonded to porous silica or ceramic microparticles 5 to 10 pun in diameter, or equivalent. Maintain the mobile phase at a pressure and flow rate capable of giving the required resolution (see below). Inject a volume, up to 25 pL, of the System Suitability Solution in a similar manner. Calculate the resolution, R (>3.6), between calcium formyltetrahydrofolate and Folic Acid by the equation... 

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