DE4418517C1 - Wear resistant coat prodn. on metal or ceramic substrate - Google Patents

Abstract

In the prodn. of a wear-resistant coat by thermal spraying of hard and/or ceramic material powder onto a metal or ceramic substrate, an inorganic lubricant, which is resistant to high temp. is incorporated in the wearing coat by impregnation in vacuum, followed by the application of pressure.

Description

The invention relates to a method for producing a Wear layer containing hard materials and / or ceramic Materials as well as high temperature resistant inorganic Lubricants on a metallic or ceramic Substrate in which the hard materials and / or ceramic Materials in powder form using a thermal Spraying on the substrate to form the Wear layer can be applied.

Hard materials are substances of great hardness and Wear resistance understood. Metallic hard materials are high-melting with a metallic character, these include - Carbides, nitrides, carbonitrides, borides and silicides Transition metals. Non-metallic hard materials are used for Example diamond, boron carbide, silicon carbide, aluminum oxide and cubic boron nitride.

Ceramic materials are made from inorganic and predominantly non-metallic compounds or elements constructed and more than 30 vol .-% crystalline materials understood that known as ceramics, glass ceramics, oxide ceramics are. In addition to clay minerals, carbides, nitrides, oxides,  Silicides used to make ceramic materials selected properties.

Wear layers made of hard materials and / or ceramic Materials are in particular metallic or ceramic substrates, preferably in thermal Coating process applied, for example Plasma spraying, flame spraying or High speed flame spraying.

Gases such as argon, helium, Nitrogen, hydrogen or their mixtures in one Torch an arc of high energy density. Here are Plasma temperatures between 12,000 and over 20,000 K reached.

These temperatures lead to a large increase in volume of the Gas that flows out of the nozzle at high speed. With the help of a carrier gas stream, e.g. B. nitrogen, the powdered spray material introduced into the plasma jet. The particles are melted and by the gas flow accelerates. The coating can not only in air, but also in vacuum, in an inert atmosphere or under water respectively.

In flame spraying, the material to be applied is wire, rod or powder form of an acetylene-oxygen flame fed and melted in the center and by means of an atomizing gas (e.g. compressed air or nitrogen) or expanding combustion gas or with the addition of a Accelerating gas, for example argon or nitrogen, hurled onto the substrate. Because of the flame temperature materials with a melting point of up to 3160 ° C a maximum of 2500 ° C can be processed using flame spraying. At This is the use of powdered spray materials Melting behavior is generally worse than with wire or Rod. Ceramic materials can only be limited process and the layers thus produced are through a high porosity. With large spray intervals porous metallic layers can also be applied.  

High-speed flame spraying takes place in one Combustion chamber under high pressure gas combustion into which powdery spray material is supplied. As fuel gases can propane, propene, ethylene, acetylene and hydrogen be used. The layers produced with this are characterized by a dense structure and smooth surfaces out.

The hard material or Ceramic layers are characterized by high Wear resistance.

With wear layers, in particular equipped with high temperature resistant wear layers In technology, substrates are diverse Areas of application needed.

From DE-OS 18 11 196, for example Wettable powder mixture of Ni-Mo-Fe alloys with 2% Mo, 81% Ni and rest Fe as binders, hard materials such as WC, ZrB₂, Cr₃C₂, TiB₂, corundum (Al₂O₃), SiO₂ or WC-Co-Cermet and Solid lubricants such as BN, MoS₂ or graphite for flame or plasma spraying on z. B. Electromagnetic friction surfaces Known couplings.

DE-OS 20 30 556 is the manufacture of piston rings with sliding surface by flame or plasma spraying of porous Metal primer made of Mo, Mo alloys, WC etc. and one Pore impregnation with dispersions of solid lubricants, such as Graphite, MoS₂, talc, mica, Zn stearate, PTFE etc. in liquid white spirit and drying at 149-204 ° C known become.

In EP-PS 144 769 the thermal spraying of Mixtures of Al-Mo-Ni alloys and ZrO₂ graphite and z. B. NiAl graphite ZrO₂ cermet on the conveyor belt continuous casting machines.  

A composite wettable powder is disclosed in EP-OS 487 273 metallic Al, Ti, Cu, Zn, Ni, Cr, Fe, Co and / or Si-containing matrix, such as Al-Si alloys or ceramic Al₂O₃-, TiO₂-, ZrO₂- and / or SiO₂-, phosphate, Perovskite or spinel-containing matrix as well as CaF₂, BN, MgF₂, BaF₂, MoS₂ etc. as solid lubricants and plastics, such as PTFE, PPS, polyimide, PFA and optionally graphite Manufacture of abradable seals for gas turbines described.

GB-PS 1083 791 describes the manufacture of a flame spray Sheathed wire with sheath made of Cu, Al or austenitic steel and Filling made of hard material such as Al203, ZrO2, TiO2, BeO, mullite, WC SiC etc. and / or solid lubricants such as graphite, Pb or MoS2 and use for wear-resistant brakes or clutches or plain bearings known.

However, it has been found that wear resistant Layers of hard materials and / or ceramic materials Often a travel claim despite post-processing Limitations due to their relatively high frictional resistance exhibit.

According to the prior art, lubricants are considered Surface coatings applied to substrates, i.e. H. she are subject to high wear due to abrasion. In particular, it is known to use inorganic lubricants Layered lattice structure, such as hexagonal boron nitride, Add molybdenum (IV) sulfide or graphite suspensions to the are based on resin or alcohol binder to hereby To produce surface coatings that are then in use need to be touched up very often.

Wear layers made of ceramic materials can be found in usually poorly wetted by metallic melts. in the In the case of glasses and slag, on the other hand, high Temperatures for wetting the melt on the surface and  surface reactions occur. Because of this, it can in various technological processes to malfunctions come.

It is known, in the cases of friction and wetting, as described above, temporary auxiliary substances in the form of lubricants. These lubricants are used in usually on the surface that of the friction or the Wetting is applied. Have lubricants However, the disadvantage that they are under appropriate stress are quickly worn out, so that complications in the Process control occur and the corresponding surfaces with renewed lubricant layers must be provided.

The invention has for its object a method for Production of wear layers from hard materials and / or ceramic materials containing high temperature resistant inorganic lubricants, to create their Friction properties and wettability is improved, such that the frictional resistance of the wear layers Hard materials and / or ceramic materials is reduced and or the wettability is reduced, d. H. a poor wettability of the wear layer is obtained.

This task is based on the generic Method solved in that the wear layer by means of of the lubricants in a vacuum with a subsequent one Pressurization is impregnated.

So it will be in addition to the hard materials and / or ceramic materials high temperature resistant inorganic Lubricants applied together with the hard materials and / or ceramic materials form the wear layer and contained in it in a fine distribution.

The application of the lubricant-containing according to the invention Wear layer on a substrate takes place in a single or multi-stage process.  

Solid lubricants are used for the process according to the invention used, preferably those with a layered grid structure, of those of graphite analog hexagonal boron nitride, graphite, molybdenum (IV) sulfide and titanium (IV) sulfide are preferred.

In addition, there are also the amorphous modifications of the Bornitrides, namely the soft amorphous boron nitride and the amorphous form of carbon used as lubricants.

By combining hard materials and / or ceramic Materials and high temperature resistant inorganic Lubricants to an integrated layer, which as Wear layer also has lubricant properties, becomes wear-resistant with the method according to the invention Lubricant layer or a lubricant-containing Wear layer created.

Hard materials in particular are used for the wear layer Base of carbides, nitrides, carbonitrides, borides, oxides or silicides of transition metals individually or in Mixtures of these are provided. In particular, oxides, Carbides, borides, nitrides and silicides of the elements magnesium, Aluminum, silicon, calcium of the metals of IV a-, V a-, VI a-th subgroup of the periodic table and / or their Alloys alone or in mixtures and / or with the addition of Nickel and cobalt are used. For the wear layer furthermore ceramic materials based on Clay minerals, carbides, nitrides, silicides and / or oxides be used.

According to the invention, the lubricants are finely divided in the Wear layer in amounts of 0.1 to 50 wt .-%, based on the hard materials and / or ceramic materials of the Wear layer, preferably in amounts of 1 to 10% by weight contain. Here, only one lubricant or one Lubricant mixture can be used.  

Impregnating a porous wear layer with Lubricants or medium containing lubricant or Lubricant-containing suspension is preferably carried out in the Vacuum with a subsequent pressurization, possibly also with the addition of heat.

Advantageous embodiments of the method according to the invention are the characterizing features of claims 2 to 9 removable.

A preferred way of introducing the lubricants into the wear layer can be done by infiltration, wherein the wear layer made of hard materials and / or ceramic materials first thermally onto a substrate sprayed on and manufactured. The substrate with the thermally sprayed porous layer of hard materials and / or ceramic materials is then, for example, in one Recipients introduced and placed under vacuum, then in the recipient through an inlet to the lubricant entered suspension containing, this suspension penetrates into the pores of the wear layer and seals them so far from. During the infiltration of the lubricants containing suspension in the porous wear layer the vacuum in the recipient is reduced and if necessary then pressure applied to completely close the pores to fill. This infiltration process can be repeated several times to completely cover the pores of the wear layer with the to fill the suspension containing lubricants. Instead of The infiltrating medium can also be a suspension Solid, like a synthetic resin or pitch, that the Lubricant optionally in bound form or as an additive contains. This medium to be infiltrated, such as synthetic resin or bad luck, is the wear layer that is in one Recipients located under vacuum, infiltrated like described above. If necessary, the Temperature increased under vacuum, so that the synthetic resin or pitch penetrates into the pores of the wear layer and through subsequent annealing polymerized or cured in air.  

Here, carbon is used as a lubricant Wear layer introduced, which remains there. When in use of pitch as the medium to be infiltrated, this is in the Recipients liquefied at elevated temperature, making it good can penetrate into the porous wear layer, with others The predominant part of volatile can increase temperature Substances of bad luck are gasified and escape again and there the carbon from the pitch remains in the porous Wear layer back, the carbon from this Pitch usually polymerizes into a network.

It is also possible to apply the lubricants to the ones already on the Wear layer made of hard materials on the substrate and / or ceramic materials during a subsequent one mechanical surface treatment of the wear layer bring in. Here, the lubricants on the Given the surface of the wear layer and for example with mechanical processing such as polishing or grinding rubbed superficially into the wear layer or brought in. This measure is particularly complementary to the previously described method steps of the even application of lubricants throughout See wear layer. This way, the High concentration on the surface of the wear layer Lubricants can be realized.

The invention finds a particularly advantageous use according to claim 10 in the equipment of substrates for the Hollow glass production.

According to the method of the invention, various Test specimen with a lubricant-containing wear layer coated. Various process variants were used Use, for which examples are described below.

example 1

Powdery zirconia was made with powdery hexagonal Mechanical boron nitride in a weight ratio of 5: 1  mixed and by means of plasma spraying on sample sheets made of St 37 applied as a substrate. In one across the way produced wear layer made of zirconium oxide, containing Hexagonal boron nitride as a lubricant was able to use the hexagonal over the entire layer thickness Boron nitride detected in the pores of the zirconium oxide layer become. The frictional resistance of those produced according to the invention Layer containing zirconium oxide and hexagonal boron nitride, was clear compared to a pure zirconium oxide layer reduced.

When using the coated substrate in the Hollow glass production slides hot glass drops over them Layer. The service life of the coated according to the invention Substrates, i. H. of the invention with lubricants equipped wear layer had a significant improved service life compared to conventional resin coated substrates used in hollow glass manufacturing were used.

Example 2

A porous ceramic was made on a substrate made of St 37 Layer based on zirconium oxide by means of plasma spraying upset. The substrate with the zirconium oxide layer was heated to approx. 200 ° C and placed in a vacuum chamber. About 30 mbar was evacuated in the vacuum chamber, and then over an inlet flooded the vacuum chamber with hard coal pitch. The hard coal hard pitch penetrated into the porous ceramic Shift one. Then it was coated and infiltrated Substrate removed from the vacuum chamber and annealed to the to remove volatile constituents of hard coal hard pitch. The porous ceramic layer remained on the base Zirconium oxide carbon from hard coal hard pitch. After that were made to measure the carbon distribution in to examine the zirconium oxide layer. This turned out to be out that almost all pores of the zirconium oxide layer with Carbon were infiltrated.  

This substrate also has a wear layer Zirconium oxide containing carbon as a lubricant increased frictional resistance and reduced wettability compared to pure zirconium oxide layers.

Example 3

A substrate, for example made of St 37, was again used a porous ceramic layer based on zirconium oxide coated with plasma spraying. The so coated Substrate was placed in a vacuum chamber. The vacuum chamber was evacuated to about 30 mbar and with a hexagonal Aqueous suspension containing boron nitride Solid content of approx. 20% by volume flooded. Subsequently the coated substrate was dried. Microscopic Investigations showed that the hexagonal boron nitride from the Suspension now evenly in the porous Zirconium oxide layer was included distributed.

This substrate also has a wear layer Zirconium oxide containing lubricant in the form of hexagonal boron nitride, showed a significantly increased Frictional resistance and a reduced wettability a pure zirconium oxide layer.

Example 4

Powdery aluminum titanate was made with powdery hexagonal Mechanical boron nitride in a weight ratio of 5: 1 mixed and by means of plasma spraying on sample sheets made of St 37 applied as a substrate. In one across the way wear layer made of aluminum titanate, containing hexagonal boron nitride as a lubricant This could be done across the entire layer thickness hexagonal boron nitride in the pores of the aluminum titanate layer be detected. The frictional resistance of the invention produced layer containing aluminum titanate and hexagonal boron nitride, compared to a pure one Aluminum titanate layer significantly reduced.  

Example 5

A porous substrate was formed on a St 37 substrate Wear layer based on aluminum oxide Plasma spraying applied. The substrate with the Aluminum oxide layer was heated to about 200 ° C and in introduced a vacuum chamber. Was in the vacuum chamber evacuated about 30 mbar, and then through an inlet Vacuum chamber flooded with hard coal hard pitch. Here penetrated the hard coal hard pitch into the porous wear layer. Then the coated and infiltrated substrate was made the vacuum chamber removed and annealed to the volatile To remove components of the hard coal hard pitch. Back remained in the porous wear layer based on aluminum oxide Carbon from hard coal hard pitch. After that Grindings made to the carbon distribution in the To investigate aluminum oxide layer. This turned out to be out that almost all pores of the aluminum oxide layer with Carbon were infiltrated.

This substrate also has a wear layer Alumina, containing carbon as a lubricant, pointed increased frictional resistance and reduced wettability compared to a pure one containing no carbon Aluminum oxide layer.

Claims (10)

1. A method for producing a wear layer containing hard materials and / or ceramic materials and high-temperature-resistant inorganic lubricants on a metallic or ceramic substrate, in which the hard materials and / or ceramic materials are applied in powder form by means of a thermal spraying process to the substrate to form the wear layer , characterized in that the wear layer is impregnated by means of the lubricants in a vacuum with a subsequent pressurization. 2. The method according to claim 1, characterized in that with a Wear layer made of ceramic materials and / or Hard material coated substrate in a recipient is placed under vacuum and the pore volume of the Wear layer with the one containing the lubricants Suspension is filled in the recipient via a Inlet is entered. 3. The method according to any one of claims 1 or 2, characterized in that the impregnation process or Infiltration process up to ten times, preferably is repeated at least five times to remove the pores of the Wear layer completely with those in the suspension fill lubricants contained. 4. The method according to any one of claims 1 to 3, characterized in that for impregnation or Infiltrate a lubricant into the porous  Wear layer a synthetic resin or pitch is used, that at elevated temperature under vacuum in the pores of the Wear layer can penetrate and by subsequent Tempering of the wear layer polymerized or on the Air cures, using lubricant in the form of carbon in the wear layer in finely divided form is introduced. 5. The method according to any one of claims 1 to 4, characterized in that the lubricants in a Amount of 0.1 to 50, preferably 1 to 10% by weight, based on the hard materials forming the wear layer and / or ceramic materials can be used. 6. The method according to any one of claims 1 to 5, characterized in that inorganic lubricants with Layered grid structure like graphite analog hexagonal boron nitride, graphite, molybdenum (IV) sulfide and / or titanium (IV) sulfide can be used. 7. The method according to any one of claims 1 to 5, characterized in that which as lubricants amorphous boron nitride and / or amorphous carbon be used. 8. The method according to any one of claims 1 to 7, characterized in that to form the Wear layer hard materials based on oxides, Carbonitrides, carbides, borides, nitrides and silicides of the elements magnesium, aluminum, silicon, calcium, the Metals of the subgroups Iva, Va or VIa des Periodic table and / or alloys alone or in Mixtures and / or with the addition of nickel and cobalt be used. 9. The method according to any one of claims 1 to 8, characterized in that to form the Wear layer ceramic materials based on  Clay minerals, carbides, nitrides, silicides and / or Oxides are used. 10. Use one with a wear layer according to one of claims 1 to 9 equipped substrate in the Hollow glass production.