Bevel-helical speed reducer B4 l radial shaft sealS ide Dual radial shaft seal Z B4-VH-8-A

Flender/Flender Gear Units/Bevel-helical speed reducer B4

t Chromium(V compounds are toxic Certain safety precautions must be taken when handling these compounds and when treatin waste water More environmentally friendly chrom- ium(VI) or chromium-free processes 3 exist, or are being discussed, for some of the sectors mentioned However, none of these alternative processes offers level of corrosion protection comparable to that of processes using chromium (VI) Thus, the goal of the project was to expand on these alternatives The chromium-free pro- cesses to be developed were to have corrosion protection properties comparable to those known from processes using chromium (VI) The overall project was divided into 3 sub-projects II 1 Rinsing of phosphate coatings . Conversion treatment of architectural aluminium Passivation of galvanised steel strip 2. Working steps ) Improvement of existing chromium-free processes, based on various complex hydro- fluoricacids, by combination with suitable organic compounds The possibilities were low- molecular compounds with corrosion-inhibiting properties and polymers with reactive groups ) Testing of selected metalorganic compounds as regards their ability to produce the desired coatings alone or in combination with the chromium-free processes mentioned in ) 3. Results 3.1 Analysis of coatings 3.1 . Galvanised steel, material ST 0-SB with double-sided, 1 [MCrlm thick zinc coating Untreated substrates and treated sheets wereanalysed using ESCA methods. theSEM, microprobe, GDOSand 8 ___ NE--6, chromium-free laboratory product, and standard roduct based on chromic acid were used for treatment The GDOS analyses of the untreatecfsheets confirm the known ele- ment distribution The expected accumulation of aluminium and lead in the surface could not be detected by ESCA Alkaline de reasing had only marginal effect on the surface Traces of sodium, phosphorus and silicon #om the solution accumulate on the surface Sulphate deposits caused byatmos- pheric in