CZ192094A3 - Surface treated material and process for producing thereof - Google Patents

Abstract

The surface-treated material has, at the surface of the substrate, for example, steel, amorphous to microcrystalline, e.g. wherein the interface between the substrate and the coating is diffuse and the coating comprises substrate elements and the substrate comprises elements coating. The coating surface may be polycrystalline or a crystalline titanium nitride layer. In his way production is first applied by magnetron sputtering a coating which is then treated by annealing or discharge

Description

Technical field

The invention falls within the technical field of surface treatment of materials.

BACKGROUND OF THE INVENTION

The interface between the substrate and the coating plays a key role in the refinement of surfaces of bodies, tools, mechanical components and structures, i.e., generally substrate surfaces, by deposition of functional and protective coatings. No coating, even though it has optimal physical and chemical properties, performs well if it does not bond perfectly to the substrate and prevents the coating from becoming detached from the substrate during its function, particularly under mechanical stress or exposure to an aggressive environment.

The perfect bonding of the coating to the substrate has not yet been satisfactorily solved and is currently one of the most complex surface engineering problems.

A standard procedure is used to achieve good bonding of the coating to the substrate. The surface of the substrate must be perfectly machined and thoroughly cleaned prior to deposition. The cleaning process consists of a number of steps ranging from mechanical cleaning, chemical cleaning, degreasing, rinsing in various chemical solutions of different temperatures, displacement of water from the surface, drying, up to ion-plasma discharge in the deposition facility in the case of physical and plasma-stimulated chemical deposition coatings.

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After performing all of the above operations, the coating may adhere well to the substrate, but the interface between the coating and the substrate is very sharp, which means that there will be no mixing of the coating and substrate elements at the interface. This is a major shortcoming of these procedures. Therefore, the adhesion of the coating to the substrate is not perfect. For many applications, adhesion is insufficient, very dependent on the chemical composition of the substrate and coating material, and very difficult to reproduce.

Therefore, there is an intensive search for ways to further improve the adhesion of the coating to the substrate. So far, two such methods are known.

The first method uses a thin intermediate layer, such as a titanium layer between a steel substrate and a hard abrasion-resistant titanium nitride layer, to improve adhesion. The function of this layer, which has been shown to improve the adhesion of the coating, is not fully explained. The titanium layer is believed to perform two functions:

1) Dissolves weak natural oxide layers, i.e. gettering chemical effect.

2) Due to its softness, it reduces shear stress at the coating / substrate interface.

However, the interface of the coating and the substrate remains sharp again and there is no mixing of the coating and substrate elements around the interface.

The second method uses a low energy implantation of the coating metal ions into the surface of the substrate, for example titanium Ti * ions, into the steel substrate prior to deposition of the hard abrasion resistant TiN layer to improve adhesion. Such implantation is carried out with titanium ions (Ti) produced, for example, in an arc discharge with cathode spots and accelerated to the substrate by a negative voltage of about 1 to 2 kV. Implantation results in the incorporation of titanium at a very low depth below the substrate surface, about 1 to 10 nm. In addition to the very low implantation depth, the main disadvantage of this method of improving adhesion is the contamination of the substrate surface with macro particles generated in an arc discharge together with titanium ions Ti *. Also, the need to combine an arc discharge which modifies the interface prior to depositing the coating, for example with a magnetron discharge, constitutes a considerable complication of the deposition device and, of course, also causes a high cost thereof.

SUMMARY OF THE INVENTION

The disadvantages of the solutions described in the prior art are eliminated by the surface-treated material according to the invention, which is characterized in that the coating of the material comprises substrate elements and the substrate comprises coating elements, the coating structure being amorphous to microcrystalline. One of the preferred alternatives of the inventive refined material is a material which additionally has either a thin barrier layer, for example titanium nitride, on the surface of its coating, increasing the concentration of diffusing elements at the coating surface, or a thin polycrystalline or crystalline layer with microstructure, phase and chemical composition. the desired resulting properties of the polycrystalline or crystalline layer.

The process according to the invention is based on a two-step process. In a first step, an amorphous to microcrystalline coating is first formed on the substrate in a known manner, for example by ion bombardment or ion cladding. The treated material is then surface treated in a second step. The surface treatment in the second step is either annealing under vacuum or in a defined atmosphere, and / or exposing the material obtained

A first step of treating the plasma with a discharge, which is particularly suitable for achieving said barrier layer on the surface of the coating, and / or depositing the polycrystalline or crystalline layer on the coating prepared in the first step.

An X-ray amorphous to microcrystalline coating applied to a perfectly machined and cleaned substrate, after subsequent treatment in a known manner, for example by annealing under vacuum or by plasma treatment and / or deposition of a polycrystalline or crystalline layer, will allow very strong interdiffusion of coating and substrate elements. coating and substrate elements down to micrometers. This creates a perfect bond between the substrate and the coating and a wide diffusion interface, which may include the entire X-ray thickness of the amorphous to microcrystalline coating.

BRIEF DESCRIPTION OF THE DRAWINGS

There are four diagrams relating to an exemplary embodiment of the invention.

Fig. 1 is an X-ray diffraction diagram of a steel substrate coated with an amorphous titanium layer.

Fig. 2 is an X-ray diffraction diagram of a steel substrate coated with a polycrystalline titanium layer.

In the diagrams shown in Fig. 1 and Fig. 2, the horizontal axis has a diffraction angle of 2Θ and the vertical axis represents the upward intensity of X-ray reflections in arbitrary units Ihkifa.u from bottom to top.].

Fig. 3 is a diagram of a depth element profile of a steel material deposited with an amorphous titanium layer after surface treatment in a second step.

Figure 4 is a diagram of a depth element profile of a steel substrate coated with a polycrystalline titanium layer.

In the diagrams shown in Fig. 3 and Fig. 4, the horizontal axis is a measure of depth from the surface of the treated material in µm, and the vertical axis is a measure of coxicentration of the elements in%.

The depth element profile diagrams were measured by GDOS (Glow discharge optical spectroscopy) using a Lečo SPD-750 spectrometer.

DETAILED DESCRIPTION OF THE INVENTION

An exemplary embodiment of the invention is a laboratory-tested surface-treated steel material and a process for its production, i.e. a laboratory-tested method of bonding steel 15330 as a substrate to a titanium layer. The chemical composition of steel 15330 is given in the following table:

Chemical composition of steel 15330

element C Mn Si (wtfc) Cr Mo IN min. 0.24 0.4 0.17 2.3 0.2 0.15 max. 0.34 0.8 0.37 2.7 0.3 0.30

First, a 20 mm diameter round plate and a 6 mm thick plate of 15330 steel, the surface of which was cleaned by a standard procedure commonly used prior to physical deposition of layers by vapor deposition, sputtering, or ion cladding on steel, was sputtered with DC magnetron with a 60 mm diameter titanium target. mm titanium layer. During deposition, the substrate was placed 45 mm from the surface

The sputtering target was heated to 200 ° C and polarized to a grounded steel deposition vessel with a negative voltage of -500 V. Sputtering was performed in argon at a discharge current of 1.34 A and a pressure of 0.3 Pa for 15 minutes. This layer was amorphous by X-ray diffraction; showed zero alpha-Ti reflection (100) and near zero alpha-Ti reflection (011), as shown in the diagram in FIG.

Figure 2 shows, for comparison, the same X-ray diffraction pattern of a typical polycrystalline titanium layer in which the bonding according to the invention cannot be made. The polycrystalline titanium layer was sputtered at a substrate bias of -100 V; the other deposition parameters were the same as the titanium layer shown in Fig. 1. Both titanium layers had the same thickness of about 4 µm.

After deposition, the steel substrate, coated with a titanium coating with a structure characterized by the X-ray diffraction pattern without reflection of FIG. 1, was heated to 550 ° C and subjected to a plasma discharge burning in a 1: 1 N2: H2 mixture at 1067 Pa for two hours. During this process, extremely strong interdiffusion of the substrate and coating elements occurred, thereby mixing the substrate and coating elements. The coating contained substrate elements and the substrate elements of the coating, as evidenced by the depth element profile shown in Fig. 3. The distribution of the elements is measured from the surface of the coating towards the substrate. The sensitivity ranges for the individual elements in Figure 3 are as follows:

Fe (100%), Ti (100%), Cr (5%), Mo (1%), and Ni (1%).

Again, the depth element profile for the polycrystalline titanium layer on the steel substrate 15330 shown in Fig. 4 is shown for comparison. The sensitivity ranges for the individual elements in Figure 4 are as follows:

Fe (100%), Ti (100%), Cr (2%), Mo (1%), and Ni (1%).

Comparison of the depth profiles in Figures 3 and 4 illustrates that the X-ray amorphousness of the titanium layer is, in accordance with the essence of the present invention, a key condition for starting the interdiffusion of the coating and substrate elements with subsequent heating and plasma treatment.

Industrial applicability

The surface-treated material according to the invention is applicable wherever it is necessary to perfectly bond the coating to the substrate of the non-refined material and to achieve a higher surface function of the coated substrate compared to the surface of the non-refined material, eg higher surface hardness, higher abrasion resistance, higher corrosion resistance, lower coefficient of friction. higher resistance to mechanical or thermal stress, better electrical, optical and magnetic properties, higher resistance to aggressive environment, etc.

The process according to the invention is applicable in surface engineering, electrical engineering, microelectronics, optics, chemical industry, medicine, decoration and packaging, and many other fields.

Claims (6)

PATENT CLAIMS 1. A surface-treated material, characterized in that the coating of the material comprises substrate elements and the substrate comprises coating elements, wherein the coating has an amorphous to microcrystalline structure. Surface-treated material according to claim 1, characterized in that on the surface of the coating there is a thin barrier layer, for example titanium nitride, increasing the concentration of diffusing elements at the coating surface. Surface-treated material according to claim 1 or 2, characterized in that the amorphous to microcrystalline coating is covered by a polycrystalline or crystalline layer, for example a titanium nitride layer, to increase the surface hardness and its abrasion resistance. 4. A method according to any one of claims 1 to 3, characterized in that an amorphous to microcrystalline X-ray coating is first formed on the substrate, for example by an ion bombardment or ion cladding, and then the substrate with the thus formed coating is surface-treated in a second step. processes. The method of claim 4, wherein the surface treatment in the second step is annealing the substrate with the coating formed in the first step, under vacuum or in a defined atmosphere. -96. The method of claim 4 wherein the surface treatment in the second step is exposing the substrate with the coating formed in the first step to plasma discharge. 7. A method according to claim 4, characterized in that the surface treatment in a second step is applied to the coating by a polycrystalline or crystalline layer in a known manner, for example by magnetron sputtering.