DD287877A5 - PROCESS FOR COATING WEAR AND HEAT-DEMANDED METAL SURFACES - Google Patents

Abstract

The invention includes a method for coating verschleisz- and heat-stressed Metallloberflaechen. The method is used to apply fill layers to one or more sprayed layers on metallic surfaces to improve the layer properties. Gemaesz the invention is applied to already existing spray coatings serving as a filling layer of alumina and / or aluminum titanate, the rock flour, in particular basalt or Diabasmehl with certain levels of SiO2 / Fe2O3 and MgO is added to achieve an optimum pore density. The application of this new process solution leads to an increase in the use value and the thermal shock resistance of the layer. The fill layers produced in this way are sealed with agents for achieving non-stick properties, improving tribological properties and corrosion protection. {Coating of Metallic Surfaces; Obtaining special fill layers; Plasma spray process; Household utensils made of aluminum}

Description

Field of application of the invention The invention relates to a method for applying special thermal Spritzschichton of non-metallic materials

metallic substrates subject to wear due to friction, heat and / or corrosion.

It is preferable to apply where thermally produced sprayed layers as filling layer for special functional materials

z. B. on the basis of PTFE u id / or organic silicone compounds are used.

A special field of application is the coating of home and kitchen appliances, which concludes with a Non-stick layer of PTFE-containing products are sealed. Characteristic of the known state of the art There are already many methods and variants derived therefrom for applying base layers as a pretreatment for the Realization of functional layers based on PTFE and / or organic silicon compounds known. Especially for household and kitchen appliances are on the inner surfaces of z. B. pans and pots u. Like. By means of thermal Spray method Hard material layers applied as base layers. This is followed by a non-stick coating with PTFE-containing products.

(Viehweg, series, Scheuerlein, Kunststoffhandbuch Bd.XI, Munich 1971, in particular S.363, DE PS 3604762).

In order to achieve a uniform and lasting formation of the PTFE-containing non-stick coating, the in the Application of the respective spraying process sporadically resulting technologically induced porosity of the hard material layer

used, however, due to the relatively small pore diameter and the distribution in the layer structure, a thin liquid sealing solution with a particle size of = 5μΓη caused.

A defined relatively large pore volume is connected to the z. Currently used spray powders based on Al ₂ O ₃ and / or Al ₂ TiO ₆

technologically -'ech controllable or result sprayed coatings with little change in temperature! 'Resistance.

Z ¹ IeI the invention

The aim of the invention is to provide a process by means of which, while avoiding the nightclubs adhering to the known solutions, an optimization of the sprayed layers serving as filling layer for sealing solutions or dispersions for selectively influencing the non-stick properties or for reducing the sliding friction is achieved and thus for increasing effectiveness of the coating system and quality improvement of the product.

Explanation of the essence of the invention The invention is based on the object, a method for selectively influencing the porosity plasma or other

thermally or by means of other energy-intensive methods of sprayed non-metallic layers on metallic

Substrates, preferably for aluminum and its alloys to develop. Such special spray coatings, so-called filler layers serve to receive sealing solutions or Sealing dispersions z. B. based on PTFE and / or organic silicon compounds. Porosity-affected layers are applied to primer or spray coatings of conventional type. The present object is achieved in that on the material technology important way of Microstructure modification the size and distribution of the gas phase in the sprayed layer (pores and bubbles) by an introduction

Of foreign substances to a spray powder of Al ₂ Oa is specifically influenced.

To change the pore density and achieve open, fillable pores is basalt or Diabasmehl with appropriate Granulation between 20-40μιτ> added to the Al ₂ O ₃ spray powder. The effect of the network-forming acidic oxides (eg SiO ₂ , TiO _2, etc.) results in the "layer-like" structure of the sprayed layer

changed.

To achieve a pore density of 15-20% at the same time finer microstructure of the filling layer can, for. B. a basalt flour or Diabase flour having a SiO ₂ / Fe ₂ Oj ratio of 1: 3.2 to 1: 3.9 and an MgO content of between 5-20%. The amount of additive is between 7-22%. Spray coatings with such properties have increased in conjunction with sprayed coatings of conventional construction Thermal shock resistance. When using AI ₂ O ₃ -based spray coatings to improve the quality of food preparation equipment

These described filling layers can be sealed with PTFE-containing non-stick agents.

The defined pore density results in connection with the PTFE seal optimal roasting properties of the so

coated frying and cooking appliances.

The interlocking of such filler layers may also be provided with agents for increasing corrosion resistance or media Reduction of sliding friction done. To achieve maximum mechanical and thermal properties of the Layer thickness proportion with increased pore volume (filling layer) amount to a maximum of 50% of the total layer thickness. embodiment The invention will be closer to an embodiment, the coating of household dishes, such as roasting, closer

to be discribed.

Prefabricated roasting utensils made of the material Al 99,5, which were processed according to the following technology

- To wash

- Applying a primer layer dur'.h plasma spraying of Al / Ni 69/31 with a layer thickness of 10pm

- Applying a carrier layer by plasma spraying of AljO ₃ with a layer thickness of 25μηη

are provided by plasma spraying with a filling layer of Al ₂ O ₃ + 15% diabase flour in a layer thickness of 15 μσι.

The generated pore density is about 20%. The filling layer is finally non-stick sealed with PTFE emulsion. Compared to the previous temperature interval for testing the thermal shock resistance of 130-180 ⁰ C is a

maximum quenching temperature of 270 ° C without any damage to the coating. The number of use tests, especially milk cook test and sugar test, has been increased by 70% without any degradation of the quality of the coating.

Claims (3)

1. A method for coating of wear and heat-stressed metal surfaces, wherein prior to applying a functional layer, first one or more layers are applied by thermal spraying, characterized in that the spray powder for receiving the functional materials serving top filling layer minerals with a SiO2 / Fe ₂ O ₃ ratio of 1: 3.2 to 1: 3.9 and a MgO content between 5 and 20% are added. 2. The method according to claim 1, characterized in that the filling layer of aluminum oxide or aluminum titanate is formed and added as additives diabase and / or basalt meals with a grain size between 20 and 40μΐη the spray powder. 3. The method according to claim 1 and 2, characterized in that the filling layer for the functional materials is 25 to 50% of the total coating thickness.