WO2014000963A1

WO2014000963A1 - Method for machining the surface of a component

Info

Publication number: WO2014000963A1
Application number: PCT/EP2013/060121
Authority: WO
Inventors: Gerhard Suenderhauf; Frank Stadler; Werner Teschner
Original assignee: Robert Bosch Gmbh
Priority date: 2012-06-29
Filing date: 2013-05-16
Publication date: 2014-01-03
Also published as: DE102012211242A1; BR112014032235A2; JP6062543B2; EP2867521A1; CN104487698A; JP2015528736A

Abstract

The invention relates to a method (100) for machining the surface of a component, in particular an injection nozzle, said method including the method steps of pretreating (120) and/or cleaning (130) the surface of the component; forming (140) a silicon layer or a silicon-containing layer on the surface of the component by means of a deposition process at a first temperature; aftertreating (150) the surface with the layer formed thereon at a second temperature which, in comparison to the step for forming the layer, is greater than the first temperature in order to reinforce a diffusion of the silicon atoms out of the layer into the component surface and/or into a region near the component surface; and removing (160) the layer formed on the surface in order to expose the surface which has been changed during the formation (140) and aftertreatment of the layer.

Description

Method for processing the surface of a component

description

The invention is based on a method for processing the surface of a component, in particular an injection nozzle, according to the preamble of patent claim 1. The invention is further based on a component, in particular an injection nozzle, with modified surface according to this method according to claim 7. In components or workpieces, which are used as in the case of injectors as fuel-carrying components of injection systems, there is the problem that fuel residues as deposits on the surfaces of the components in contact with the fuel can deposit. In particular in the area of the injection holes of injection nozzles, deposits on the surface of the injection holes from the fuel residues may impair the functionality of such an injection nozzle over time. By coating the fuel-bearing surfaces with protective coatings which are chemically reactive with respect to the fuel residues, an attempt is made to limit the deposit formation. From DE 10 2006 017 449 A1 a system for injecting pressurized fuel into the combustion chamber of an internal combustion engine is known, wherein the system comprises at least one component component having a cavity and / or a bore, wherein during operation of the system at least one inner wall of the cavity and / or the bore is in contact with pressurized fuel and wherein the at least one inner wall has at least one protective coating to be applied to the fuel. The protective coating serves to avoid the effect of corrosion and abrasion on the inner wall.

From DE 10 2008 044 024 A1 discloses a PE-CVD coating process for coating metallic workpieces, in particular of components of fuel injection systems is known, wherein the metallic workpieces with a high-frequency AC voltage or a pulsed or unpulsed DC voltage is applied and exposed to a plasma stream from a gas distributor. It is provided that the workpieces are arranged stationary relative to the gas distributor. The protective layer obtained by means of the coating process is based on hydrocarbons and / or silanes and is resistant to abrasion. In addition, it serves to protect the workpieces from corrosion.

From WO 2000051732 A1 a method for changing a solid surface is known. In this case, in a first process step hydrogen-containing amorphous silicon on the surface by thermal decomposition at an elevated temperature of

Silicon hydride gas is deposited to form silane radicals which recombine to coat the surface with hydrogen-containing amorphous silicon, and in a second process step the coated surface is functionalized by subjecting the substrate to a reagent having an unsaturated hydrocarbon group under a predetermined pressure and an elevated temperature for a predetermined period of time.

Advantages of the invention

The method having the features of patent claim 1 has the advantage that the substrate surface of a component covered by the applied layer changes during the process by the process step of coating by diffusing into the surface zone of the substrate silicon impurity atoms and, due to this indiffusion, the chemical Physical properties of the surface zone are changed, and in a further process step, the deposited layer is removed, wherein the substrate surface is changed during the diffusion is exposed. The changed by the diffusion of silicon foreign atoms surface zone is rendered inert after removal of the layer, that is, for example, with respect to fuel residues reaction poor and therefore counteracts a deposit formation. In particular, when applying the method according to the invention to fuel-carrying components such as injectors in the function-sensitive area of the spray holes whose spray hole surfaces, ie their mantle surfaces, according to the invention changed so that they behave chemically largely inert to fuel residues, thereby counteracting a coating-forming and thus cross-sectional narrowing coking the Spritzmantelflä- chen so that the reliability and thus the life According to the invention treated injectors remains largely maintained over a long period. It is also advantageous that the internal cross-section of the injection holes and their associated characteristic characteristic achieved by the hydroerosive rounding performed as standard in a pretreatment of an injection nozzle is substantially restored on account of the removal of the applied layer at the end of the method according to the invention.

Further advantageous developments and refinements of the invention will become apparent from the measures listed in the dependent claims.

According to an advantageous embodiment of the method according to the invention, with which the surface buried under the formed layer is defined and exposed in series production of components with high reproducibility, the removal of the layer takes place in at least one cleaning step by means of ultrasonic cleaning with a thickness of the formed Layer and on the type of a detergent used in this period of time. In addition, according to a development of the method according to the invention for removing the layer, it is exposed to an alkaline solution. For this purpose, an alkaline solution having a strongly basic pH, preferably having a pH of about 14, is used.

According to an embodiment of the method according to the invention which can be carried out inexpensively and is technically relatively easy to control, the method step for forming the layer on the surface of the component takes place by means of chemical vapor deposition. Hydrogen-containing amorphous silicon is deposited on this surface to form the layer on the surface.

drawings

An embodiment of the invention is explained in more detail in the following description and in the accompanying drawings. The latter shows in a schematic representation:

1 shows a flowchart with the essential process steps of the method according to the invention for changing the surface of a component, FIG. 2 shows the component in cross-sectional view at the beginning of the method according to the invention, FIG. 3 shows the component of FIG. 2 with a silicon layer formed on the surface thereof, during which a diffusion of silicon atoms from the silicon layer into the region of the component close to the surface takes place during a process step of the after-treatment

FIG. 4 shows the component of FIG. 3 following a method step according to the invention, the silicon layer formed on the surface of the component being removed and the silicon atoms diffused out of the layer remaining in the region of the component close to the surface.

Description of the embodiment

The flowchart designated in its entirety by 100 in FIG. 1 illustrates the essential process steps of the method according to the invention for processing or changing the substrate surface of a component. After a first process step 110, in which the component is manufactured, this component is subjected to a pretreatment in a step 120, for example by injecting the injection ports thereof

hydroerosive rounding. In a subsequent process step 130, the surface of the component is cleaned by means of a chemical cleaning solution such as acetone. This wet cleaning step 130 serves to ensure the chemical cleanliness of the substrate surface of the component to be subsequently vapor-deposited. Thereafter, in a further process step 140, in which the component is used in a reaction chamber, ie a reactor, formed on the cleaned surface of the component, a layer by means of CVD ("chemical vapor deposition") or chemical vapor deposition as a silicon layer or As at least silicon-containing layer is vapor-deposited or deposited on the surface at a process temperature or growth temperature of about 400 ° C., hydrogen-containing amorphous silicon is applied to the surface In this process step 140 changes due to the increased process temperature of about 400 ° The surface or surface zone of the substrate of the component is characterized by a diffusion process initiated thereby, in which silicon atoms from the layer diffuse into the surface or surface zone. In a subsequent process step 150, the process temperature T is compared to that in the preceding Increased step 140 set first temperature to a second temperature, so that T> 400 ° C, in order to continue the process already introduced in the previous step 140 diffusion process of silicon impurities from the deposited layer in the surface zone of the substrate and thereby to continue the physico-chemical change of the surface zone of the substrate of the component.

Subsequently, in a process step 160, this grown-up layer is essentially completely removed in order to expose the physically and chemically modified surface of the component by forming the layer according to step 140 and by the aftertreatment according to step 150. For this purpose, the previously coated in accordance with process step 140 and after step 150 aftertreated component in an ultrasonic bath is cleaned with a dependent on the thickness of the layer formed and the type of detergent used therein, in the preferred embodiment, in which the layer thickness of the layer at about 100 to 500 nm, is about 45 minutes. In addition, the layer is removed by means of an alkaline solution, such as acetone, which has a strongly basic pH, which preferably corresponds to a value of about 14. This pH environment is chosen so that in the preferred application of a steel-formed component a sufficiently large distance to the critical pH of pH = 5, at which stainless steels rust, to comply.

Fig. 2 illustrates the component 1 at the beginning of the method according to the invention for processing the surface 2 after the process step 130, i. after cleaning the surface 2 of the component 1. Fig. 3 illustrates the component 1 with trained on the surface 2

Silicon layer in a process step during the process step 150, which serves for the aftertreatment of the surface 2. Due to the second temperature set in process step 150, which is higher than the first temperature set in the previous process step 140, the diffusion of silicon atoms 4 from the layer 3 already initiated in step 140 into the surface 2 and the underlying near-surface region of the component 1 continued and strengthened.

4 illustrates the component 1 following the method step 160 serving to remove the layer 3. In this case, the layer 3 formed on the surface 2 (see FIG. 3) is removed and the surface near the surface 2 and the underlying surface Area diffused silicon atoms 4 remain there as embedded in the microstructure of the component 1 impurities. Due to the incorporation of the silicon impurities 4 in the microstructure of this detected by the diffusion process surface zone of the component 1, the physical properties of the surface 2 and thus their chemical properties change see.

In summary, the method 100 according to the invention serves for processing or changing the surface of a component or workpiece, in particular an injection nozzle, and comprises the method steps of pretreating 120 and / or cleaning the surface of the component, forming a silicon layer or silicon-containing layer the surface of the component as a substrate by means of deposition at a predetermined temperature, the aftertreatment 150 of the surface with the layer formed thereon at a higher temperature than the step for forming the layer, to a diffusion of silicon impurities from the layer into a surface zone of the sub Strengthen strats of the component, and the ablating 160 of the surface formed on the layer to bare the surface modified by the formation of the layer 140, which, due to the diffusion processes, a physico-chemical change of the surface zones structure and consequently has a chemically largely inert behavior, in particular with regard to fuel residues.

Claims

claims

1 . Method (100) for machining the surface of a component, in particular an injection nozzle, with the following method steps:

- pretreating (120) and / or cleaning (130) the surface (2) of the component (1);

- forming (140) a silicon layer or silicon-containing layer (3) on the surface (2) of the device by means of deposition at a first temperature;

Aftertreating (150) the surface (2) with the layer (3) formed thereon at a second temperature, which is greater than the first temperature, compared with the step (140) for forming the layer, in order to prevent diffusion of silicon atoms (4 ) from the layer into the surface and / or to reinforce a near-surface region of the component;

- removing (160) the layer (3) formed on the surface (2) in order to expose the surface which has changed during the formation and after-treatment of the layer.

2. The method according to claim 1, characterized in that the removal (160) of the layer (3) takes place in at least one cleaning step by means of ultrasonic cleaning with a dependent on the thickness of the formed layer (3) and the type of detergent used in this period of time.

3. The method according to claim 1 or 2, characterized in that for removing (160) of the layer (3) it is exposed to an alkaline solution.

4. The method according to claim 3, characterized in that for removing (160) of the layer (3) an alkaline solution having a strongly basic pH, preferably having a pH of about 14, is used.

5. The method according to claim 1 to 4, characterized in that the step for forming (140) of the layer (3) on the surface (2) of the component takes place by means of chemical vapor deposition.

6. The method according to claim 5, characterized in that for forming (140) a layer (3) on the surface (2) hydrogen-containing amorphous silicon is deposited on the surface.

7. component, in particular an injection nozzle, with according to the method according to any one of claims 1 to 6 modified surface.