JP2008076044A - Method and device for coating starter element used for combustion process of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve particularly heat resistance. <P>SOLUTION: Coating material 3 is coated to a starter element 1 and/or a protection layer already coated on the starter element 1 by a coating method originated from a plasma method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for coating a starting element, in particular a sheath type glow plug, used in a combustion process in an internal combustion engine.

  The invention further relates to a device for coating a starting element, in particular a sheath type glow plug, used in the combustion process in an internal combustion engine.

  Based on the ever-increasing emission policy for combustion equipment, especially internal combustion engines, however, there is always a demand for improvement in the ambient conditions for the combustion process in order to improve the efficiency of the combustion equipment. The main factor for influencing the combustion process of low hazardous substances and favorable consumption is the temperature generated during the combustion process.

  Commercial starting elements used in combustion processes in internal combustion engines, particularly sheathed glow plugs used in diesel engines, are more or less stable for temperatures up to a maximum of about 1100 ° C. When operating within the higher temperature range, its operating life is dramatically reduced based on the aggressive corrosive agents that are generated in the combustion chamber. In particular, oil ash and soot formation components erode the starting element accordingly.

  The object of the present invention is therefore to improve a starting element of the type mentioned at the outset so that an improvement in particular with respect to heat resistance is possible.

  In order to solve this problem, in a first method according to the invention, the coating material is applied to the starting element and / or to the protective layer already applied to the starting element by a deposition method resulting from the plasma process. I made it.

  Furthermore, in order to solve the above-mentioned problems, in the second method of the present invention, the starting element is heated before and / or during the coating process.

  According to an advantageous embodiment of the method of the invention, a heating element arranged on the starting element is used for heating the starting element.

  According to an advantageous embodiment of the method of the invention, the coating material is applied in a partially molten state.

  According to an advantageous embodiment of the method of the invention, another protective layer is applied to the starting element and / or to the protective layer already applied to the starting element.

  According to an advantageous embodiment of the method of the invention, an adaptation is made between the thermal expansion coefficient of the starting element or the layer applied to the starting element and the thermal expansion coefficient of the protective layer to be applied.

  According to an advantageous embodiment of the method of the invention, the formation of the individual protective layers on the starting element is such that the composition of the protective layers changes from the substrate material to the main component of the coating material from the inside to the outside. To implement.

  According to an advantageous embodiment of the method of the invention, the formation of the individual protective layers on the starting element can be achieved when the protective layer composition is relatively Al-rich from a relatively Si-rich material from the inside to the outside. Or it changes so that it may change to a yttrium rich material.

  According to an advantageous embodiment of the method according to the invention, the formation of the individual protective layers on the starting element is carried out in such a way that the protective layer composition is relatively Implement to change to chromium-rich or molybdenum-rich material.

According to a preferred embodiment of the method of the present invention, the coating material is an acidic and alkaline glass former, such as an alkali salt, sulfate, phosphate and the like, at a temperature greater than about 1150 ° C. For example, corundum (α-Al ₂ O ₃ ), Y ₂ O ₃ , magnesium spinel (MgAl ₂ O ₃ ), zircon dioxide (ZrO ₂ ), chromium oxide (Cr ₂ O ₃ ), Aluminum oxide (Al ₂ O ₃ ) and / or mixtures of such oxides are used.

According to a preferred embodiment of the method of the present invention, the coating material is an acidic and alkaline glass former, such as an alkali salt, sulfate, phosphate and the like, at a temperature greater than about 1150 ° C. mixed oxides of resistance to, for example, mullite _{(3Al 2 O 3 · 2SiO 2} ) or Y similar compounds: Y silicate _{(Y 2} O 3 2SiO ₂₎ and / or yttrium stabilized zirconium dioxide ( YZS) is used.

  According to a preferred embodiment of the method of the present invention, the coating material is an acidic and alkaline glass former, such as an alkali salt, sulfate, phosphate and the like, at a temperature greater than about 1150 ° C. A material consisting of a material system based on tungsten carbide (WC), which does not belong to the group of oxides or mixed oxides, for example WC, WC / Co, WC / CoCr, WC / CrNi or Use something similar to this.

  According to an advantageous embodiment of the process of the invention, a catalytically active material, such as a Ce, Pt, Pd compound or the like, is deposited.

  According to an advantageous embodiment of the method according to the invention, the coating material is used in the form of spherical or nearly spherical particles or granules.

  According to an advantageous embodiment of the method of the invention, the outer layer of the protective layer is formed as a closed layer.

  According to an advantageous embodiment of the method of the invention, one of the layers of the protective layer is formed as a porous layer.

  According to an advantageous embodiment of the method of the invention, the deposition method has a sputtering process.

  According to an advantageous embodiment of the method of the invention, the deposition method comprises a thermal spraying process.

According to an advantageous embodiment of the method of the present invention, used as a starting element to be coated, ceramic, for example, _Si 3 _{N 4} or _SiO x _{C y} and / or metal, for example, a substrate made of NiCr _o Fe _r.

  Furthermore, in order to solve the above-described problems, the first apparatus of the present invention is provided with a plasma coating apparatus.

  Furthermore, in order to solve the above-mentioned problems, the second device of the present invention is provided with means for enabling heating of the starting element before and / or during the coating process.

  Correspondingly, the invention relates to a method for coating a starting element, in particular a sheathed glow plug, used in the combustion process in an internal combustion engine. This method is characterized in a first solution by applying the coating material to the starting element and / or to a protective layer already applied to the starting element by means of a deposition method resulting from the plasma process. In the plasma method, for example, nitrogen plasma or argon plasma can be formed. This plasma can be inexpensively processed in the normal ambient atmosphere (APS technology). The plasma process has the advantage that the coating material to be deposited is heated very well and uniformly and even partially melted by the high temperatures, in this case occurring, possibly above 6000 ° C. . This allows the coating material to be applied to the surface to be coated in a partially melted state. The resulting melt bond with the foundation and the bond between the particles to be deposited has a particularly advantageous influence on the adhesion and strength of this layer.

  In a second solution, it is proposed for the method for coating such a starting element to heat the starting element before and / or during the coating process, whereby the coating process This makes it possible to adapt the temperature of the starting element to the temperature of the coating material to be applied. The basis of this measure is to minimize the temperature difference between the starting element and the material to be deposited by the coating, while at the same time providing the layer to be deposited on the individual layer plane, in particular the starting element or the sheathed glow plug. There is recognition that a significant reduction in material stress in the anchoring region can be obtained. This allows a lower stress, dense and possibly thicker layer structure with correspondingly improved mechanical properties compared to a coating layer deposited without temperature adaptation.

  In addition to improving the mechanical resistance capability of the starting element thus coated, an important advantage of this measure is that the coating layer thus applied compares the starting element even at operating temperatures significantly higher than 1100 ° C. To protect against destructive corrosive action over a long period of operation.

  Heating of the starting element to optimize the coating process can be realized in an advantageous way by operating the heating means specific to this starting element. This allows, for example, direct heating during the coating process in the plasma installation via a controlled voltage. Thereby, adjustment of the temperature of the starting element can be realized, for example, via a corresponding influence on the supply voltage.

  However, in addition to this direct heating of the starting element, other means, for example pre-temperature regulation or a two-stage process via a pre-formed second plasma flame: 1. heating of the plug by plasma flame; Pre-temperature adjustment is also possible via the start of the coating process or the like.

  Especially by the combination of heating of the starting element and plasma coating, in the dense and mechanical stresses that adhere particularly well between the coating layer to be applied and the subsequent coating layer already applied to the starting element or to the starting element. Relatively few bonds can be realized.

The starting element or the sheath type glow plug has a substrate in the sense of the present invention. This substrate may optionally have already been subjected to a pretreatment in order to further improve the adhesion of the coating layer to be applied. For this purpose, a mechanical pretreatment such as grinding, roughening or the like, a chemical pretreatment such as etching with a suitable acid or alkaline solution such as NaOH solution or a binder material such as nano-SiO ₂ -X (OH) 2x "Aerosil (registered trademark)" can be used for undercoating.

  In order to obtain particularly good protection against the starting element, further protective layers may be applied to the starting element and / or to protective layers already applied to the starting element. In other words, depending on the type of coating of one starting element based on the multiple layers to be applied, it is particularly advantageous for the coefficient of thermal expansion of the starting element or the layer already applied to the starting element and the subsequent protective layer to be applied. It is even possible to meet the thermal expansion coefficient of For this purpose, the materials of the individual layers that are desired to be deposited can be selected in harmony with one another in view of the optimization of the coefficient of thermal expansion between the individual layers that are desired to be bonded.

  It is particularly advantageous that the individual protective layers are applied to the starting element such that the composition of the individual protective layers changes from the relatively Si-rich material to the relatively Al-rich material from the inside to the outside. A structure is proposed. By such means, for example, a total protective layer consisting of three individual layers can be realized for one starting element. The total protective layer consists of a thin film surface layer with weak corrosion protection, an intermediate layer with average corrosion protection, and a final outer layer with excellent corrosion protection.

  As a material for carrying out such a coating method, oxides or mixed oxides are particularly suitable. This is because this oxide or mixed oxide can be deposited in a relatively inexpensive process step. However, some materials that cannot be assigned to the oxide or mixed oxide group, such as metals, carbides or nitrides, are outstandingly suitable for such coating methods.

In order to carry out such a coating process from the group of oxides, it is particularly advantageous to use Y ₂ O ₃ (yttrium oxide), corundum (α-Al ₂ O ₃ ), magnesium spinel (MgAl ₂ O ₃ ), dioxide Zircon (ZrO ₂ ), chromium oxide (Cr ₂ O ₃ ), aluminum nitride (AlN) and / or mixtures of such oxides are proposed. Because these materials are extremely resistant to acidic and alkaline glass formers such as alkali salts, sulfates, phosphates and the like at temperatures greater than about 1150 ° C. It is.

A group of mixed oxides, for carrying out such coating method, Y silicate _(Y 2 _Si 2 _{O 5)} or _{(3Y 2 O 3 2SiO 2)} , mullite _{(3Al 2 O 3 · 2SiO 2} ) And / or yttrium stabilized zircon dioxide (YZS) is proposed to be particularly advantageous. In order to carry out corresponding coating processes from a group of materials not belonging to oxides or mixed oxides, material systems based on tungsten carbide (WC), for example WC, WC / Co, WC / CoCr, WC / It is proposed that CrNi or the like is particularly advantageous.

  Another advantageous property can be imparted to the starting element or the coating layer desired to be deposited on the starting element by the use of catalytically active materials, such as Ce, Pt, Pd compounds or the like. This makes it possible, for example, to reduce the amount of erodible substances and / or substance mixtures that surround the starting element during its operation. This is possible even at very high temperatures, especially in the range of greater than about 1150 ° C., in part 1300 ° C. and even more, due to the increased lifetime.

  As a particularly advantageous form for carrying out such a coating method, spherical or nearly spherical particles or granulated parts are proposed for the coating material. This is because the particles or granulated parts can be treated particularly advantageously on the one hand and, on the other hand, the sealing properties of the layers to be applied by the coating method can be influenced well. Because it makes it. As a particularly advantageous particle size, values between 0.5 μm and 10 μm are considered.

  Depending on the desired properties, the outer layer of the protective layer that is to be applied by such a coating method may be formed as a closed layer or a porous layer. A closed layer has the advantage of protecting all areas of the layer below it as uniformly as possible. In contrast, in a porous configuration, for example, a layer deposited below the outer layer, a fuel mixture surrounding the outer layer and / or an erosive corrosive agent generated from the fuel mixture during the combustion process Additional protection of the outer layer can be obtained against reaction with.

  As a deposition method for carrying out the coating method, for example, a sputtering process or a spraying process may be proposed, for example in connection with the coating material used or another process parameter. A possible layer thickness of one anticorrosion layer may be, for example, 30 μm to 500 μm. The possible porosity of one anticorrosion layer may be between 0% and 60%, for example.

Furthermore, the coating method, as a starter element to be coated, ceramic, for example, _Si 3 _{N 4} or _SiO x _{C y} and / or metal, for example, can be characterized by a substrate made of NiCr _o Fe _r are used.

  The invention further relates to a device for coating a starting element, in particular a sheath type glow plug, used in a combustion process in an internal combustion engine. The apparatus is characterized in that correspondingly suitable plasma equipment is provided for performing a sputtering process and / or a thermal spraying process for the deposition of a corresponding coating material on the starting element. In addition, such a type of coating device is a heating device for heating such a type of starting element before and / or during the coating process, or a correspondingly formed internal element of the starting element. A heating element can be connected and supplied, so that the starting element is heated directly.

  In addition, the invention relates to a corresponding starting element for use in the combustion process in an internal combustion engine, in particular a sheath type glow plug. This sheath type glow plug has a protective layer. This protective layer is applied to the starting element by one of the methods described above.

  In the following, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a very schematic plan view of a starting element 1 used in the combustion process in an internal combustion engine. This starting element 1 is coated by the device 2 to protect against corrosive action at high temperatures in the range greater than about 1150 ° C.

  The main aspect of the method for coating the starting element 1 is that the coating material 3 is protected on the substrate 9 of the starting element 1 and / or already applied to the starting element by a deposition method based on the plasma process. To be applied to the layer 10 (see FIG. 2). In order to carry out the plasma process, the device 11 is shown symbolically. In a particularly inexpensive configuration, the device 11 may be a nitrogen plasma facility or an argon plasma facility. This facility can work in normal ambient atmosphere (APS technology).

  As a deposition method, not only plasma spraying but also sputtering may be considered. In this case, in plasma spraying, the particles of the coating material 3 fly through a high-temperature plasma flame of up to 6000 ° C. in a partially melted state, and then collide with the surface to be coated and partially melt-bonded to this surface. Combined by.

  Also, another advantageous method proposes heating the starting element 1 in order to improve the adhesion of the coating material 3 to be applied. This is achieved in this embodiment by contact of the heating element 4 embedded in the starting element 1 via the connection 5 and the line 6. For positioning or fixing the starting element, a correspondingly formed holder 7 is provided. This holder 7 may have a supply connection 8 for supplying energy to the heating element 4.

  A particularly good material bond between the particles of the coating material 3 to be deposited by the coating method and the surface on which the particles impinge can be obtained by a combination of the two methods. This is because this allows a significant reduction in material stress between the individual materials compared to a starting element that is not heated. In addition, for the protective layer 10 thus applied, the advantage is obtained that a relatively high density can be achieved with correspondingly improved mechanical properties.

  Corresponding to FIG. 2, in order to improve the corrosion resistance of the starting element 1, another protective layer 12 is applied to the starting element 1 and / or to the protective layer 10 already applied to the starting element 1. Good.

  It is particularly advantageous when the start-up element 1 is subjected to a coating process to match between the thermal expansion coefficient of the starting element or the layer 10 applied to the starting element and the thermal expansion coefficient of the protective layer 12 to be applied. You may be broken. This is an important factor for improving the quality of the anticorrosion layer to be deposited with respect to layer adhesion and life. This is due to the value of the coefficient of thermal expansion of the material to be bonded to each other, for example the substrate 9 and the first layer 10 to be deposited or the thermal expansion of the already deposited layer 10 and the subsequent layer 12 to be deposited. This is possible by selecting the coefficient values to be as slightly different as possible. If the values of the coefficients of thermal expansion of the two layers are too different, a stepwise adaptation of the individual values of the coefficient of thermal expansion (WAK) due to the deposition of a plurality of individual layers may be achieved.

From this viewpoint, for example, a material system: silicon nitride [WAK: about 3.0 × 10 ⁻⁶ K ⁻¹ ], quartz [WAK: about 1.2 × 10 ⁻⁶ K ⁻¹ ], mullite [WAK] : About 5.6 × 10 ⁻⁶ K ⁻¹ ] and corundum [WAK: about 7.8 × 10 ⁻⁶ K ⁻¹ ]. This material system may be bonded together in the following order:
- Silicon nitride _(Si 3 _{N 4)} - (relative HAT anticorrosion) substrate material
- Quartz (SiO ₂₎ - the surface layer of the thin film substrate (weak corrosion)
-Mullite (3Y ₂ O ₃ · 2SiO ₂ ) -Intermediate layer (average corrosion protection)
Corundum (α-Al ₂ O ₃ ) —outermost layer (excellent corrosion protection).

  Thus, a structure consisting of a plurality of overlappingly deposited layers that are continuously sprayed onto the starting element allows a stepwise adaptation of the WAK and thus an advantageous deposition of the desired protective material. Furthermore, in this example, the chemical composition transition is made fluidly (from the inner Si-rich material to the outer Al-rich material), allowing good material compatibility across the layer.

  Particularly advantageously, the oxides and mixed oxides already mentioned above are used as the coating material 3 when carrying out such a coating process. However, materials that do not belong to the group of oxides or mixed oxides, such as material systems based on tungsten carbide, are also outstandingly suitable for such coating methods.

  In addition, the deposition of catalytically active materials is also advantageously considered. This catalytically active material may be disposed, for example, as the second to last layer 12 below the porous coating layer 13.

  In FIG. 2, the configuration of the outer layer 13 or the covering layer 13 is illustrated as a dense layer 13A on the right half and illustrated as a porous layer 13B on the left half. All applied layers together have a protective layer 14 in common.

1 is a schematic view of a starting element to be coated and a coating device used in a combustion process in an internal combustion engine. FIG. 2 is a schematic partial cross-sectional view of the starting element shown in FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Start element, 2 Apparatus, 3 Coating material, 4 Heating element, 5 Connection part, 6 Line, 7 Holder, 8 Supply connection part, 9 Base | substrate, 10 Protection layer, 11 Apparatus, 12 Protection layer, 13 Coating layer, 13A layer , 13B layer, 14 protective layer

Claims (21)

  In a method for coating a starting element (1) used in a combustion process in an internal combustion engine, in particular a sheath type glow plug (1), the covering material (3) is applied to the starting element (1) by a deposition method resulting from the plasma method. And / or a protective layer (10) already applied to the starting element (1). A method for coating a starting element used in a combustion process in an internal combustion engine.   In a method for coating a starting element (1) used in a combustion process in an internal combustion engine, in particular a sheath type glow plug (1), the starting element (1) is heated before and / or during the coating process. A method for coating a starting element for use in a combustion process in an internal combustion engine.   3. The method according to claim 1, wherein the heating element (4) arranged on the starting element is used for heating the starting element (1).   4. The method as claimed in claim 1, wherein the coating material (3) is applied in a partially melted state.   5. The protective layer according to claim 1, wherein a further protective layer is applied to the starting element and / or to the protective layer already attached to the starting element. 6. the method of.   A fit between the thermal expansion coefficient of the starting element (1) or the layer (10) applied to the starting element (1) and the thermal expansion coefficient of the protective layer (12) to be applied is made, The method according to any one of 5 to 5.   The formation of the individual protective layers (10, 12, 13) on the starting element (1) is such that the composition of the protective layers (10, 12, 13) is the main component of the coating material from the substrate material toward the outside. The method according to claim 1, wherein the method is carried out so as to change to   The formation of the individual protective layers (10, 12, 13) on the starting element (1) is compared from a material in which the composition of the protective layer (10, 12, 13) is relatively Si rich from the inside to the outside. The method according to any one of claims 1 to 7, wherein the method is carried out so as to change into a typical Al-rich or yttrium-rich material.   The formation of the individual protective layers (10, 12, 13) on the starting element (1) is such that the composition of the protective layers (10, 12, 13) is relatively rich in Fe (iron) from the inside to the outside. 9. A method according to any one of the preceding claims, wherein the method is carried out to change from a material to a relatively chromium rich or molybdenum rich material. The coating material (3) is an oxide that is resistant to acidic and alkaline glass formers such as alkali salts, sulfates, phosphates and the like at temperatures greater than about 1150 ° C. Corundum (α-Al ₂ O ₃ ), Y ₂ O ₃ , magnesium spinel (MgAl ₂ O ₃ ), zircon dioxide (ZrO ₂ ), chromium oxide (Cr ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ) and / or 10. The process as claimed in claim 1, wherein a mixture of such oxides is used. As coating material (3), mixed oxides resistant to acidic and alkaline glass formers, such as alkali salts, sulfates, phosphates and the like, at temperatures greater than about 1150 ° C., for example mullite _{(3Al 2 O 3 · 2SiO 2} ) or Y similar compounds: using Y silicate _{(Y 2} O 3 2SiO ₂₎ and / or yttrium stabilized zirconium dioxide (YZS), claim 1 11. The method according to any one of up to 10.   As a coating material (3), an oxide or an acid or alkaline glass former, such as an alkali salt, sulfate, phosphate and the like, resistant at temperatures greater than about 1150 ° C. A material comprising a material system based on tungsten carbide (WC) not belonging to the group of mixed oxides, such as WC, WC / Co, WC / CoCr, WC / CrNi or the like, is used. 12. The method according to any one of 1 to 11.   13. A method according to any one of claims 1 to 12, wherein a catalytically active material, such as a Ce, Pt, Pd compound or the like, is deposited.   14. A method as claimed in claim 1, wherein the coating material (3) is used in the form of spherical or nearly spherical particles or granules.   15. A method according to any one of claims 1 to 14, wherein the outer layer (13) of the protective layer (14) is formed as a closed layer (13A).   16. A method according to any one of the preceding claims, wherein one of the layers (13) of the protective layer (14) is formed as a porous layer (13B).   The method according to claim 1, wherein the deposition method comprises a sputtering process.   The method according to claim 1, wherein the deposition method has a thermal spraying process. As coated should start element (1), a ceramic, for example, _Si 3 _{N 4} or _SiO x _{C y} and / or metal, for example, NiCr _o using a substrate consisting of Fe _r, any one of claims 1 to 18 the method of.   In an internal combustion engine characterized in that a plasma coating device (11) is provided in a device for coating a starting element (1) used in a combustion process in an internal combustion engine, in particular a sheath type glow plug (1). Device for coating the starting element used in the combustion process.   In an apparatus for coating a starting element (1) used in a combustion process in an internal combustion engine, in particular a sheath type glow plug (1), heating of the starting element (1) is carried out before and / or during the coating process. A device for coating a starting element for use in a combustion process in an internal combustion engine, characterized in that it is provided with means (4) enabling it.

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