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Adhesive Manufacturing Processes Chapter 5: Joint Element Materials Univ.-Prof. Dr.-Ing. Prof. h.c. Stefan Böhm Fachgebiet Trennende und Fügende Fertigungsverfahren (tff) Universität Kassel Quelle: Wikipedia Agenda  Introduction  Adhesive Properties - Metal  Adhesive Properties – Synthetic Materials  Adhesive Properties - Glass  Adhesive Properties – Wood  Adhesive Proerties - FVK-Materials  Material Combinations  Conclusion 2 Introduction  Surface Layers of Metalic Materials Foreign Substance Layer Adsorption Layer Reactionary Layer Metallic Basic Material Boundary Layer Schematic depiction of the surface layers of metallic material (Source: Habenicht) 3 Introduction Depiction of the relevant layer thickness in relation to each other Adsorption Layer Reactionary Layer Metallic Base Material Boundary Layer – Adsorption Layer – Reactionary Layer – Boundary Layer ● The foreign substance layer (dirt) has no defined thickness. (Source: Habenicht) 4 Introduction Foreign Substance Layer Boundary Layer Adsorption Layer Reactionary Layer  Layer Thickness: 0.1-100μm Metallic Nase Material Boundary Layer  The boundary layer is formed by deformation processes and/or through cutting and is very strong. (Source: Habenicht, S.2965ff) 5 Introduction Foreign Substance Layer Reactionary Layer Adsorption Layer Reactionary Layer Thickness: 0.01-0.1 µm Metallic Base Material Boundary Layer The reactionary layer is formed by chemical changes within the boundary layer. ● This reaction can be natural or can be caused intentionally This layer is connected strongly to the boundary layer through primary valence bonds The reactionary layer is primarily responsible for the formation of adhesion forces (lSource: Habenicht) 6 Introduction Foreign Substance Layer Adsorption Layer Adsorption Layer Reactionary Layer Thickness: 0.001-0.01µm Metallic Base Material Boundary Layer The adsorption layer is formed through the intake of molecules from the environment. ● The formation processes are mostly reversible. (Source: Habenicht) 7 Introduction Foreign Substance Layer Dirt Adsorption Layer Reactionary Layer Metallic Base Material Boundary Layer Layer thickness cannot be defined The foreign substance layer (dirt) can be made of: ● Oil ● Dust ● Greases ● Humididty (Source Habenicht) 8 Introduction Foreign Substance Layer Metallic Coatings Adsorption ayer Reactionary Layer Metallic Base Material Boundary Layer Further surface layers can be created by adding metallic coatings. ● for example in galvanized/ tinned plates, ● plated aluminium alloys or ● metallised plastics These layers lie between the boundary layer and the reactionary layer. (Source: Habenicht) 9 Introduction  As described in the chapter regarding the adhesive forces, the surface energies are significant for the adhesive bonding possibilities Surface Energy [mN/m] Iron 2550 Titanium 2050 … … Silver 1250 … PVC 40 … … PTFE (Teflon) 19  The surface energy has a direct impact on the quality of the wetting, which again is the prerequisite for an optimal adhesion 10 Introduction  This allows the general conclusion that, as regards surface energies, metal bonds are unproblematic. ● Surface energies > 1000 mN/m  Difficulties occur when the surface has negative properties: ● Oiled surface (protection against corrosion) ● not very solid oxide layer ● roughness (viscosity of the adhesive) ● … 11 Introduction  Synthetics have much lower surface energies, which limits the possibilities, if bonding adhesively without prior treatment. ● Surface energies between 19 mN/m and 47 mN/m  Depending on the synthetic, further negative properties can influence the adhesive bonding properties.This is very important to regard concerning the ageing resistance: ● contained softeners ● separating agents on the surface 12 Introduction  Apart from metallic and synthetice surfaces, there is another surface structure that is especially porous ● This includes: – wood, plywood, balsa wood, chipboards, veneers, cork – paper, cardboard, carton – textiles, felt, leather – porcelain, ceramic, terracotta, concrete, marble, artificial stones – plastic foam  Speciality: micro-mechanical form lock, mechanical adhesion 13 Agenda  Introduction  Adhesive Properties - Metal  Adhesive Properties – Synthetic Material  Adhesive Properties - Glass  Adhesive Properties – Wood and Ceramics  Adhesive Properties – FVK-Materials  Material Combinations  Conclusion 14 Adhesive Properties - Metal Corrosion Resistant Steels – Stainless Steel 15 Corrosion Resistant Steels – Stainless Steel Characteristics ● After formation of passive layer very good corrosion resistance ● high-strength and wear-resistant ● weldable ● temperature-resistant ● hygenic ● conductive 16 Corrosion Resistant Steels – Stainless Steel Fields of Application ● When a high resistance to weather is needed, especially in long-term conditions. ● Chemical Industry ● Medical Industry althammer.de ● Food Industry UNIPACK 17 Corrosion Resistant Steels – Stainless Steels The most important corrosion resistant steels ● V2A - X5 Cr Ni 18 10 (WNr.: 1.4301) – food industry, chemical machiners... (33% of the production) ● V4A - X2 Cr Ni Mo 17 13 2 (WNr.: 1.4404) – pharmaceutics, medicine und dentistry… (highly resitant to chlorine containing media) ● V4A - X6 Cr Ni Mo Ti 17 12 2 (WNr.: 1.4571) – chemical machinery, submarine constructions… ● As well as austenitic Cr Ni-steels 1.4376 and 1.4377 18 Corrosion Resistant Steels – Stainless Steel Adhesive Properties of the Surface ● The steels form a passive layer at the surface – this is mainly based on the amount of containeds chrome which reacts with the surrounding oxygene. ● The passive layer leads to a chemically hardly reacting surface ● This strongly limits intermolecular bonds and bonds created through chemisorption 19 Corrosion Resitant Steels – Stainless Steel Possible Surface Treatments: Degreassing and cleaning SACO ● Sufficient resistance to ageing Mechanical Pretreatments (grinding, brushing, blasting) ● Good starting hardness ● Adhesive bond that is sensitive to the materials 20