Nowadays there is a wide range of different organic, inorganic and composite materials, which are an important basis for the social, cultural and economic development of our society. More and more different construction and raw materials are coming into contact for years to decades in modern construction as well as numerous branches of industry. The focus is on sustainability, the combination of ecology, economy and social issues. Plastics in particular, which play an important role in this process and which include sealants/adhesives, present new challenges for everyone involved. The possible migration of plasticisers between the materials as well as various other undesirable chemical reactions must be ruled out to avoid possible incompatibilities between two building materials (or auxiliary materials).
This construction and raw material compass is intended to help in the search for a sensible way of sealing or bonding different substrates together. The content of this search engine is based on years of practical experience and our own laboratory. Please note that the definition of certain material surfaces and qualities is often difficult and this search engine can only serve as guidance without any guarantee. We always recommend obtaining sufficient information from the supplier in order to find the best possible pre-treatments for the subsequent sealing/adhesive bonding. Sufficient self-tests/own tests are definitely sensible and also necessary.
The effects of moisture can cause corrosion damage to metal. Here, the metal does not always need to be directly exposed to the moisture. Where there are seals/adhesions between metals and absorbent materials (e.g. wood, concrete, etc.), moisture can diffuse onto the metal surface through the absorbent construction material. In order to avoid this, the metalling adhesion/sealing surface should have appropriate corrosion protection!
Thanks to high surface energies, metals can generally be sealed/adhered well. However, aluminium, chrome, brass, stainless steel and various other metals/alloys can be the exceptions here. In their initial rolled, drawn, cast and forged state, undefined oxide layers, separating agents and lubricants, cutting oils, drawing greases, etc. frequently mean that the adhesive strength of the sealant/adhesive is lacking. Surface pretreatment is generally required in order to achieve sufficient adhesion and aging-resistant adhesive bonds. However, even with pretreatment of the metals/alloys, no definitive statements can be made regarding the wettability of the surfaces.
Mechanical surface pretreatment processes (grinding, brushing, abrasive blasting) improve the surface activity, but may have a negative impact on the adhesion properties to some extent because contaminations are distributed over the surface in places. Anodizing, chrome-plating, phosphating or “pickling” in acids or bases as possible pretreatments differ in their variety, their age and possible additional treatments e.g. with waxes/oils. Various powder coatings on the substrate surfaces may contain additives such as paraffin/wax or even PTFE which in turn interfere with the wettability of the adhesive surfaces.