DE102018211387A1 - Wear protection layer arrangement and component with wear protection layer arrangement - Google Patents

Abstract

In the case of a wear protection layer arrangement (10) with a substrate (11), an adhesion promoter layer (12) formed on the substrate and at least one protective layer (15) which closes outwards and is designed as an amorphous hydrogen-containing carbon layer, it is provided that a region on the substrate side (15 ') of the amorphous hydrogen-containing carbon layer (15) is doped with silicon as a dopant, and an outside area (15 ") remains undoped. Between the adhesion promoter layer (12) and the amorphous hydrogen-containing carbon layer (15) there can be two transition layers The transition layers (13, 14) can each have a lower silicon doping than the substrate-side region (15 ') of the amorphous carbon layer (15) ,

Description

The invention relates to a wear protection layer arrangement according to the preamble of claim 1 and further to a component according to claim 9 and a method for producing a wear protection layer arrangement according to the preamble of claim 10.

State of the art

Components that are exposed to high temperatures and high pressures, as is the case in particular with components of high-pressure injection systems (common rail injectors), are provided with wear protection layers as standard. Amorphous hydrogen-containing carbon layers are used as wear protection layers, which are applied to the components by means of plasma-assisted deposition processes and have a temperature resistance of up to approximately 350 ° C.

Basic research results (cf. [1] SS Camargo, Jr, AL Baia Neto, RA Santos, FL Freire, Jr, R. Carius, F. Finger "Improved high-temperature stability of Si incorporated aC: H films", Diamond and Related Materials 7 (1998) 1155-1162 ; and [2] AL Baia Neto, RA Santos, FL Freire, Jr, SS Camargo, Jr, R. Carius, F. Finger, W. Beyer "Relation between mechanical and structural properties of silicon-incorporated hard aC: H films", Thin Solid Films 293 (1997) 206-211 ) with regard to growth and characterization of thin carbon layers indicate that silicon doping of thin amorphous carbon layers increases the thermal resistance to higher temperatures, but drastically worsens the wear resistance of such carbon layers.

epiphany

Advantages of the invention

The wear protection layer arrangement with the characterizing features of claim 1 has the advantage that it has an extended temperature resistance up to about 500 ° C with practically undiminished high wear resistance. For this purpose, it is provided that a region on the substrate side of the amorphous hydrogen-containing carbon layer is doped with silicon as a dopant, and an outer region remains undoped. Due to the selective silicon doping of the area of the amorphous carbon layer on the substrate side, the silicon oxygen built in there, which diffuses into the network structure via cavities that expand at elevated temperatures, can bind to silicon oxide compounds, thereby forming a diffusion barrier for oxygen, which prevents oxidation of the underlying adhesion promoter layer made of chromium with resulting crack formation between the adhesion promoter layer and the amorphous carbon layer and at least partial delamination of the latter; As the upper area of the amorphous carbon layer remains undoped, ie free of silicon as a dopant, a "pure" hydrocarbon network with its specific microstructure and therefore its characteristic hardness and wear resistance is formed in this substrate-side area.

Further advantageous developments and refinements of the invention result from the measures listed in the subclaims.

A preferred development of the invention, with which a consistently high quality with regard to wear resistance can be achieved, is that the substrate-side region of the amorphous hydrogen-containing carbon layer has a silicon doping profile which is set in such a way that it is in a concentration value range from 1 to 20 at .-% in relation to network constituents of the amorphous hydrogen-containing carbon layer. Starting from an interface of the carbon layer, the silicon doping profile comprises an increasing profile section of increasing silicon concentration, a plateau area with an approximately constant maximum concentration of the silicon dopant, and a falling profile section with a silicon concentration falling to zero level. Reaching the zero level defines the end of the substrate-side area and at the same time the beginning of the outside area of the amorphous carbon layer.

Test series have shown that it is expedient if the thickness of the region of the amorphous carbon layer doped with silicon on the substrate is approximately 20 to 80%, preferably approximately 50%, of the layer thickness of the carbon layer.

According to one embodiment of the invention, with which a particularly high wear resistance of the wear protection layer arrangement can be achieved with a layer hardness of the amorphous carbon layer of approximately 35 GPa at approximately 500 ° C., at least one transition layer is provided which is between the adhesion promoter layer and the amorphous hydrogen-containing carbon layer. Layer is formed, wherein the at least one transition layer can be continuously doped with silicon as a dopant. The at least one transition layer has a lower silicon doping compared to the substrate-side region of the amorphous carbon layer in order to “flow” cause doping transition to the substrate-side region of the amorphous carbon layer.

An alternative embodiment of the invention can consist in that two successive transition layers are formed between the adhesion promoter layer and the amorphous carbon layer, the transition layer adjoining the amorphous carbon layer having an at least the same or slightly higher silicon doping concentration compared to the one below and has a transition layer adjacent to the adhesion promoter layer. In this embodiment, this results in a diffusion barrier for oxygen diffusing in from the outside in terms of the layer thickness.

A component with such a wear protection layer arrangement is suitable for use at high temperatures and pressures and is therefore suitable as a component of a high-pressure injection system, in particular as an injector.

In a method for producing a wear protection layer arrangement, wherein an adhesion promoter layer is formed on a substrate and then at least one amorphous hydrogen-containing carbon layer is produced directly or indirectly as a protective layer, it is provided that when the at least one amorphous hydrogen-containing carbon layer is produced, a region on the substrate side the amorphous carbon layer is doped with silicon as a dopant and an outside region of the amorphous carbon layer is formed undoped. The region on the substrate side is formed with a silicon doping profile, which is selected such that the doping profile in a plateau lies in a concentration range of 1 to 20 at .-% in relation to the process gases used in producing the amorphous carbon layer, whereby a reproducible high manufacturing quality can be achieved. For the doping profile, starting from an interface of the carbon layer, an increasing profile section with increasing silicon concentration, a plateau area with an approximately constant maximum silicon concentration, and a falling profile section with an approximately zero silicon concentration in the substrate-side area are formed , The amorphous carbon layer is generated by means of plasma-induced deposition (PECVD: "plasma enhanced chemical vapor deposition"), with one or more thin layer (s) either containing the adhesion promoter layer made of a metal such as e.g. Chromium or one or more transition layer (s) applied to the adhesion promoter layer, the amorphous hydrocarbon layer is formed by growth.

list of figures

• 1A einen Schnitt durch eine erfindungsgemäße Verschleißschutzschichtanordnung, die ein Substrat, eine Haftvermittlerschicht, zwei Übergangsschichten und eine nach außen abschließende Funktionsschicht umfasst, wobei die als amorphe Kohlenstoff-Schicht ausgebildete Funktionsschicht einen mit Silizium dotierten substratseitigen Bereich und einen undotierten oberflächenseitigen Bereich aufweist,
• 1B ein Schaubild, das ein typisches Silizium-Dotierungsprofil für den substratseitigen Bereich der Funktionsschicht veranschaulicht, wobei entlang der Abszisse die Schichtdicke der Funktionsschicht und entlang der Ordinate das Silizium-Dotierungsprofil als Funktion der Dicke der Funktionsschicht aufgetragen sind.
• 2A einen Schnitt durch die erfindungsgemäße Verschleißschutzschichtanordnung gemäß einer zweiten Ausführungsform, welche ein Substrat, eine Haftvermittlerschicht und eine als amorphe Kohlenstoff-Schicht ausgebildete Funktionsschicht umfasst, wobei die Funktionsschicht einen mit Silizium dotierten substratseitigen Bereich und einen undotierten oberflächenseitigen Bereich aufweist, sowie
• 2B ein Schaubild, das ein Silizium-Dotierungsprofil für den substratseitigen Bereich der Funktionsschicht der Schichtanordnung gemäß der zweiten Ausführungsform von 2A veranschaulicht, wobei entlang der Abszisse die Schichtdicke des substratseitigen Bereichs der Funktionsschicht und entlang der Ordinate die Konzentration der Silizium-Dotierungsprofils aufgetragen sind.

Embodiments of the invention are explained in more detail in the following description and in the accompanying drawings. The latter show in schematic views:

• 1A 3 shows a section through a wear protection layer arrangement according to the invention, which comprises a substrate, an adhesion promoter layer, two transition layers and a functional layer that closes off from the outside, the functional layer designed as an amorphous carbon layer having a substrate-doped region on the substrate side and an undoped region on the surface side,
• 1B a diagram illustrating a typical silicon doping profile for the substrate-side region of the functional layer, the layer thickness of the functional layer being plotted along the abscissa and the silicon doping profile as a function of the thickness of the functional layer along the ordinate.
• 2A 4 shows a section through the wear protection layer arrangement according to the invention in accordance with a second embodiment, which comprises a substrate, an adhesion promoter layer and a functional layer designed as an amorphous carbon layer, the functional layer having a region doped with silicon on the substrate and an undoped region on the surface, and
• 2 B FIG. 3 shows a diagram that shows a silicon doping profile for the substrate-side region of the functional layer of the layer arrangement according to the second embodiment of FIG 2A illustrates, the layer thickness of the substrate-side region of the functional layer being plotted along the abscissa and the concentration of the silicon doping profile being plotted along the ordinate.

Description of the embodiments

1A shows a wear protection layer arrangement according to the invention in a highly schematic cross-sectional view 10 that successively from a substrate 11 , one on the substrate 11 applied adhesion promoter layer 12 , a first transition layer 13 , a second transition layer 14 and a final protective or functional layer 15 is formed. As a substrate 11 A component is typically made of steel and is intended for coating in order to improve its wear resistance and temperature resistance. The one on the substrate 11 applied adhesion promoter layer 12 consists of crystalline chromium, whereas the two transition layers applied to it 13 . 14 as Chromium carbide connection structures are formed and essentially differ from one another with regard to the chromium / carbon ratio in order to adapt them microscopically to the functional layer subsequently applied 15 to effect. The final functional layer 15 is formed as an amorphous hydrogen-containing carbon layer (aC: H layer) and by means of a plasma-assisted deposition process on the second transition layer 14 applied in a layer thickness, which can be about 0.1 µm to a few µm depending on the application.

The temperature resistance of the amorphous hydrogen-containing protective layer 15 to increase is their substrate-side area 15 ' , ie the second transition layer underneath 14 adjacent area, doped with silicon. The thickness of the region doped in this way is 15 ' about 20 to 80% of the total thickness of the protective layer 15 , This also means the wear resistance of the protective layer 15 the remaining outer area remains 15 " , ie to the outside or surface 15 '"of the functional layer 15 facing surface or that of the second transition layer 14 opposite area, undoped.

The one between the adhesive layer 12 and the functional layer 15 arranged two transition layers 13 . 14 serve a gradual transition from the crystalline structure of the substrate 11 to the amorphous network structure of the functional layer 15 manufacture; both transition layers can be used 13 . 14 be doped with silicon in the exemplary embodiment and the second transition layer 14 has a slightly higher silicon doping concentration than the first transition layer 13 to reduce residual stresses from interface to interface. The two transition layers 13 . 14 each have a significantly weaker silicon doping concentration than the substrate-side region 15 ' the amorphous carbon layer.

1B illustrates in a highly schematic diagram the qualitative course of the silicon doping profile as a function of the layer thickness z of the amorphous carbon layer 15 , The thickness z of the protective layer is on the abscissa 15 is plotted, while the ordinate shows the silicon doping level N (Si). The doping profile 20 , which is formed in the shape of a trapezoid, has a rising edge 21 on that in the interface 16 of the substrate-side area 15 ' to the second transition layer 14 uses, the silicon admixture or the silicon portion in the process gas increases by a plateau region 22 the doping profile 20 to reach where the silicon admixture maintains a relatively constant maximum level Nmax, whereupon finally a falling edge 23 the doping profile 20 with which the silicon admixture is reduced from the constant maximum level Nmax to zero level, ie 0 at .-%; reaching the zero level on the falling edge 23 defines the end of the substrate-side area 15 ' and on the other hand the beginning of the outer undoped area 15 " the protective layer 15 , The silicon doping profile therefore runs over the region on the substrate side 15 ' the carbon layer 15 , Furthermore, the silicon doping profile is in the region on the substrate side 15 ' the amorphous carbon layer 15 chosen so that it lies in a concentration range that is from 1 to 20 at .-% (atomic percent) in relation to the hydrocarbon-containing process gases introduced for the deposition of the carbon layer, such as acetylene (C ₂ H ₂ ), methane or others Hydrocarbons extends, with a silicon-containing process gas such as silane being added or admixed for the silicon doping during the deposition process. The constant maximum level Nmax of the silicon concentration in the plateau area 22 is about 20 at .-% in the embodiment. After thermal aging, it follows that both the layer thickness and the layer hardness of the carbon layer 15 show an approximately constant course up to T ≈ 450 ° C and only decrease the layer thickness and layer hardness by approximately 30% at 450 ° C ≤ T ≤ 500 ° C.

2A shows a wear protection layer arrangement 100 according to a second embodiment, which differs from that in 1A illustrated embodiment differs in that intermediate transition layers are missing, so that the wear protection layer arrangement 100 successively from the substrate 110 , the chrome adhesive layer 120 and the amorphous hydrogen-containing carbon layer 150 is formed as a functional layer. The carbon layer has 150 - In accordance with the first embodiment - two adjacent areas 150 ' and 150 ' on, of which the to the interface 160 to the adhesion promoter layer 120 immediately adjacent area on the substrate side 150 ' is doped with silicon as a dopant, while the outside region facing the outside 150 ″ 150 ' remains undoped.

2 B shows in a highly schematic diagram the qualitative course of the silicon doping profile 200 in functional dependence on the layer thickness or the layer growth z of the amorphous carbon layer 150 the layer arrangement 100 according to the second embodiment of 2A , The silicon doping profile 200 runs over the substrate-side area 150 ' and comprises three profile sections, namely initially a rising flank 210 , then a plateau 220 and finally a falling edge 230 , which three zones z ₁ , z ₂ , z _{3 of} the area 150 ' assigned; there is the area 150 ' divided into the first zone z ₁ , which is an edge zone to the interface 160 forms the second - intermediate - zone z ₂ and the third zone z ₃ , which is an edge zone to the outside area 150 ' forms. The rising edge 210 extends over the first zone z _{1 of} the area 150 ' along the z-axis in a range of values of 10% ≤ z ₁ ≤ 25% of the layer thickness of the amorphous carbon layer 150 , the plateau area 220 extends over the second zone z _{2 of} the area 150 ' in a range of 5% ≤ z ₂ ≤ 40% of the layer thickness of the carbon layer 150 , and the falling edge 230 extends along the z-axis over the third zone z _{3 of} the area 150 ' in a range of 1% ≤ z ₃ ≤ 20% of the layer thickness of the amorphous carbon layer 150 , The relatively flat rise of the flank 210 causes residual stresses between the crystalline interface 160 and adjacent edge of the amorphous area 150 ' can only occur at a low level during the relatively steep slope of the flank 230 between the third zone and the adjacent, also amorphous area 150 ' takes place and therefore causes hardly any structural internal stresses. The same performance occurs as in the embodiment of 1B ,

From a procedural point of view, the following steps are provided for producing the wear protection layer arrangement: First, the chromium adhesion promoter layer is formed on the substrate or the substrate surface by deposition by means of cathode sputtering (“sputtering”); in an optional step, two transition layers are then formed on the chrome adhesion promoter layer by deposition, acetylene being deposited by means of CVD (“chemical vapor deposition”) and a silicon-containing gas being added for silicon doping of the transition layers; and finally, in a final process step, the amorphous hydrogen-containing carbon layer 15 . 150 created by a substrate-side area 15 ' . 150 ' the amorphous carbon layer 15 . 150 is doped with silicon as a dopant and an outside area 15 " . 150 ' the amorphous carbon layer 15 . 150 is undoped, the substrate-side region 15 ' . 150 ' with a silicon doping profile 20 . 200 is formed, which is selected such that it is in a concentration value range of 1 to 20 at .-% in relation to that when producing the amorphous carbon layer 15 . 150 process gas used, for example acetylene or methane. For the doping profile, starting from an interface of the carbon layer, an increasing profile section with increasing silicon concentration, a plateau area with an approximately constant maximum silicon concentration, and a falling profile section with an approximately zero silicon concentration in the substrate-side area are formed , The amorphous carbon layer is generated by means of plasma-assisted deposition (PECVD: “plasma enhanced chemical vapor deposition”).

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Non-patent literature cited

• S.S. Camargo, Jr, A.L. Baia Neto, R.A. Santos, F.L. Freire, Jr, R. Carius, F. Finger "Improved high-temperature stability of Si incorporated a-C: H films", Diamond and Related Materials 7 (1998) 1155-1162 [0003]
• A.L. Baia Neto, R.A. Santos, F.L. Freire, Jr, S.S. Camargo, Jr, R. Carius, F. Finger, W. Beyer "Relation between mechanical and structural properties of silicon-incorporated hard a-C: H films", Thin Solid Films 293 (1997) 206-211 [0003]

Claims (11)

Wear protection layer arrangement with a substrate, an adhesion promoter layer formed on the substrate and at least one protective layer closing to the outside, which is designed as an amorphous hydrogen-containing carbon layer, characterized in that a substrate-side region (15 ';150') of the amorphous hydrogen-containing carbon layer ( 15; 150) is doped with silicon as a dopant, and an outside area (15 ";150") remains undoped. Wear protection layer arrangement after Claim 1 , characterized in that the substrate-side region (15 ';150') of the amorphous hydrogen-containing carbon layer (15, 150) has a silicon doping profile (20; 200) which is set so that it is in a concentration value range from 1 to 20 at .-% in relation to network constituents of the amorphous hydrogen-containing carbon layer (15; 150). Wear protection layer arrangement after Claim 2 , characterized in that the silicon doping profile (20; 200) starting from an interface (16; 160) of the carbon layer (15; 150) has an increasing profile section (21; 210) of increasing silicon concentration, a plateau region (22; 220) with an approximately constant maximum concentration of the silicon dopant, and a falling profile section (23; 230) with an approximately zero level silicon concentration. Wear protection layer arrangement according to one of the Claims 1 to 3 , characterized in that the thickness of the silicon-doped substrate-side region (15 ';150') of the amorphous carbon layer (15; 150) is approximately 20 to 80% of the layer thickness of the carbon layer (15; 150). Wear protection layer arrangement according to one of the Claims 1 to 4 , characterized in that at least one transition layer (13, 14) is provided, which is formed between the adhesion promoter layer (12) and the amorphous hydrogen-containing carbon layer (15), the at least one transition layer (13, 14) being continuously coated with silicon as Dopant is doped. Wear protection layer arrangement after Claim 5 , characterized in that the at least one transition layer (13, 14) has a lower silicon doping compared to the substrate-side region (15 ') of the amorphous carbon layer (15). Wear protection layer arrangement after Claim 5 or 6 , characterized in that two successive transition layers (13, 14) are formed between the adhesion promoter layer (12) and the amorphous carbon layer (15), the transition layer (14) adjoining the amorphous carbon layer (15) being at least the same has a large or somewhat higher silicon doping concentration compared to the underlying transition layer (13) adjacent to the adhesion promoter layer (12). Wear protection layer arrangement according to one of the Claims 1 to 4 , characterized in that the adhesive layer (120) is followed directly by the amorphous carbon layer (150) as the functional layer, the functional layer having the substrate-containing region (150 ') doped with silicon and the undoped region (150 ") on the surface. Component with a wear protection layer arrangement according to one of the preceding claims. Method for producing a wear protection layer arrangement, an adhesion promoter layer being formed on a substrate and then at least one amorphous hydrogen-containing carbon layer being produced directly or indirectly as a protective layer, characterized in that when the at least one amorphous hydrogen-containing carbon layer (15; 150) is produced a substrate-side area (15 ';150') of the amorphous carbon layer (15; 150) is doped with silicon as a dopant and an outside area (15 ";150") of the amorphous carbon layer (15; 150) is undoped , Procedure according to Claim 10 , characterized in that the substrate-side region (15 ';150') is formed with a silicon doping profile (20; 200), which is selected such that it is in a plateau in a concentration value range of 1 to 20 at .-% im Ratio to the process gases used in producing the amorphous carbon layer (15; 150).

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