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Formore than 50 years Poligrat has dealt exclusively with the development and

application of chemical and electrochemical processes for pickling, polishing,passivation, deburring and colouring of metal surfaces

Poligrat was founded in 1952 in Munich, Germany,asa development

laboratory,Poligrat today is amedium

sized group comprising 12 subsidiary companies in Germany,France, the UK,Switzerland, Hungary,USA and Canada as well as

aworldwide network of licensees and sales partners

The Poligrat-Group has approximately

220 employees with a turnover of ca.£25M

Pitting corrosion potential of 316 Stainless across aweld (weld, heat effected zone &surface of steel)

As alternative process to the traditional pickling and passivating of Stainless Steel POLIGRAT offers POLINOX-Protect an environmentally friendly alternative. It is an economic and safe process which as an additional benefit provides a substantial increase in corrosion resistance above that of traditional methods and doesn't alter the external dimensions of acomponent.

Pickling and passivating of Stainless Steel 34 SURFACEWORLD january 2013 50% of aweld seam treated using POLINOX-Protect

POLINOX-Protect is awater based solution of aspecial proprietary blend of chemicals, which are biologically degradable and not poisonous. The application does not produce noxious or dangerous fumes.

Within the passive layer and within scale and heat discolourations POLINOX-Protect cracks iron oxides, which reduce the corrosion resistance into iron and oxygen. The free iron then is removed along with any iron contamination on the surface. The Oxides of Chrome and Nickel remain untouched, and form an improved passive layer.

In an optional second step following treatment with POLINOX-Protect the structure and consistence of passive layers can be significantly improved by a short heat treatment at temperatures between 140°C and 220°C. The resulting improvement in corrosion resistance is even higher than that of pickling passivating or electro-polishing.Itiscomparable to that of higher alloys grades of Stainless steel.

(continued on page 36) read online

Pickling and Passivating of Stainless Steel and New EnvironmentallyFriendly Brightening process forBrass

As one of the acknowledged leader’s in marketing and technology,the actual core competence of Poligrat is to develop and produce its own processes. Numerous patent applications protect the extensive know how and the market position of POLIGRATprocesses and products which are available for the treatment of most metals and alloys. The main part of our activities concerns the improvement of surface quality and the functional behaviour of stainless steel and nickel based alloys and awide variety of other metals. Through its experienced staff and efficient laboratories, Poligrat has the extensive knowledge necessary to develop solutions for the new and complex demands of industry.

provides afinal cleaning of surfaces, removing weld scale, heat discolouration and iron contamination, enabling the formation of an undisturbed and uniform passive layer to provide corrosion resistance to the base substrate.

Traditionally hydrofluoric acid, nitric acid or sulphuric acid are used to chemically remove the upper layer of the material including the existing passive layer and impurities to provide ametallic clean surface, on which anew and homogeneous passive layer can be formed. Due to health & safety and environmental risks the application of these acids is subject to restrictions and rigid controls by various agencies.

POLINOX-Protect works in anew revolutionary way: Unlike traditional pickling and passivation the existing passive layer is not removed but its structure and composition is improved, resulting in afinal structure where the corrosion resistance is greatly superior to pickled and passivated surfaces.

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