EP2102125A1

EP2102125A1 - Quartz glass component with reflector layer and method for producing the same

Info

Publication number: EP2102125A1
Application number: EP07857521A
Authority: EP
Inventors: Waltraud Werdecker; Rolf Gerhardt; Juergen Weber
Original assignee: Heraeus Quarzglas GmbH and Co KG
Current assignee: Heraeus Quarzglas GmbH and Co KG
Priority date: 2006-12-22
Filing date: 2007-12-13
Publication date: 2009-09-23
Also published as: DE102006062166A1; WO2008077807A1; JP5432721B2; JP2010513198A; DE102006062166B4; KR101111659B1; CN101568497B; KR20090100372A; US20090316268A1; IL198953A; US7947335B2; IL198953A0; CN101568497A

Abstract

Methods for producing a quartz glass component with reflector layer are known in which a reflector layer composed of quartz glass acting as a diffuse reflector is produced on at least part of the surface of a substrate body composed of quartz glass. In order, taking this as a departure point, to specify a method which enables cost-effective and reproducible production of uniform SiO2 reflector layers on quartz glass components, it is proposed according to the invention that the reflector layer is produced by thermal spraying by means of SiO2 particles being fed to an energy carrier, being incipiently melted or melted by means of said energy carrier and being deposited on the substrate body. In the case of a quartz glass component obtained according to the method, the SiO2 reflector layer is formed as a layer which is produced by thermal spraying and has an opaque effect and which is distinguished by freedom from cracks and uniformity.

Description

Quartz glass component with reflector layer and method for producing the same

The invention relates to a method for producing a quartz glass component with a reflector layer by producing a reflector layer of quartz glass acting as a diffuse reflector on at least part of the surface of a substrate body made of quartz glass.

In addition, the invention relates to a quartz glass component having a reflector layer, comprising a substrate body made of quartz glass whose surface is at least partially covered by an SiO ₂ reflector layer acting as a diffuse reflector.

Quartz glass components are used for a variety of applications, such as in the manufacture of lamps as cladding tubes, pistons, cover plates or reflector support for lamps and radiators in the ultraviolet, infrared and visible spectral range, in chemical apparatus construction or semiconductor manufacturing in the form of reactors and equipment from Quartz glass for the treatment of semiconductor devices, carrier trays, bells, crucibles, protective shields or simple quartz glass components, such as tubes, rods, plates, flanges, rings or blocks.

In lamps, the temporal constancy and the efficiency of the emitted working radiation play an important role. Even with heaters, it usually comes to low heat loss. In order to minimize radiation losses, optical radiators and radiant heaters are therefore provided with a reflector.

The reflector is fixedly connected to the respective radiator or it is a separate from the radiator reflector component.

In order to reduce the transmission or to change the transmitted lightwave spectrum, it is known to matt lamp bulbs, for example by etching with acid or by coating the lamp bulb in the interior with a partial chenförmigen, light-scattering powder, such as a mixture of clay and silicon dioxide. So far, the surfaces of particularly high-quality reflectors, which can be used in a chemically aggressive environment, without the reflector material takes damage and the reflectance decreases noticeably, made of gold. Reflector layers of gold are expensive and only limited temperature and temperature change resistant. In addition, the reflection is significantly wavelength-dependent and decreases significantly in the UV range.

These disadvantages are avoided by the method for coating quartz glass surfaces for the purpose of changing their reflectivity according to DE 10 2004 051 846, from which a reflector and a production method of the type mentioned at the outset are also known.

Therein it is proposed to form a diffusely reflecting reflector layer of at least partially opaque quartz glass. The reflector layer is produced by means of a slurry process, in which a highly filled, pourable, aqueous SiO ₂ slurry is produced which contains amorphous SiO ₂ particles. The amorphous SiO ₂ particles are produced by wet milling of SiO ₂ grains and have a particle size in the range up to a maximum of 500 μm, with SiO ₂ particles having particle sizes in the range between 1 μm and 50 μm making up the largest volume fraction.

The SiO ₂ slickener is in the form of a slip layer on the quartz glass

Substrate body applied, and then the slurry layer is dried and vitrified to form a more or less opaque quartz glass layer. For applying the slurry layer to the base body, spraying, electrostatically assisted spraying, flooding, spinning, dipping and spreading are suggested.

The quartz glass layer produced in this way can be used as a diffuse reflector for radiation over a wide wavelength range. However, it has been found that the flow behavior of the known highly filled slurry is not optimally suitable for some of the coating techniques mentioned, and therefore the reproducible production of a uniform coating in individual cases difficult. It is also a multi-step process that involves the application of the slurry layer, drying and vitrification. In all process stages, defects and thus material losses can occur, in particular shrinkage cracks and mechanical damage of the layer, which has not yet completely solidified.

The invention is therefore based on the object to provide a method which enables a cost-effective and reproducible production of uniform SiO ₂ reflector layers on quartz glass components.

In addition, the object of the invention is to provide a quartz glass component obtained by the method, which is characterized by a crack-free and uniform SiO ₂ reflector layer.

With regard to the manufacturing method, this object is achieved on the basis of a method of the type mentioned in the present invention, that the reflector layer is produced by thermal spraying by SiO ₂ particles supplied to an energy carrier, by means of this or melted and deposited on the substrate body.

In the method according to the invention, the reflector layer is produced by thermal spraying. In this case, SiO ₂ particles in the form of a fluid mass, such as powder, sol or suspension (dispersion), supplied to an energy carrier are at least partially melted and spun onto the prepared surface of the substrate body to be coated at high speed. The energy source is usually a fuel gas-oxygen flame or a plasma jet, but can also be designed as an arc, laser beam or the like.

It is important that the SiO ₂ particles are melted on and deposited on the substrate body, without a completely transparent surface layer is formed without sufficient reflectance, which would then be useless as a reflector layer for diffuse reflection. However, a limited transparency to subregions of the reflector layer is acceptable and can even be achieved. wishes to be, such as for the sealing of surface areas. A transparency-reduced opacity of the layer can also be compensated by a greater layer thickness.

In the method according to the invention, the coating of the substrate body surface and the solidification of the layer takes place in a single operation. The problems associated with the known method because of its multi-step and any damage to a not yet solidified layer are thus avoided. In particular, no shrinkage cracks occur.

It has been shown that by means of the method according to the invention, an opaque, firmly adhering, uniformly dense and, in particular, crack-free SiO ₂ surface layer can be produced which, moreover, is distinguished by adhesive strength and which is suitable as a diffuse reflector for radiation over a wide wavelength range is.

Sufficient softening of the SiO ₂ particles takes place at a temperature which can be achieved both by means of a low-energy flame spraying and arc spraying method and by means of a high-energy plasma spraying method.

In a first preferred variant of the method it is therefore provided that the reflector layer is produced by plasma spraying, wherein a plasma jet or laser beam is used as the energy carrier.

The plasma spraying allows a comparatively high energy input as well as high speeds when spin-coating the molten or fused SiO ₂ particles onto the substrate body surface. As a result, relatively thick and firmly adhering reflector layers can be produced in a short time.

The SiO ₂ particles are generally supplied to the plasma flame in powder form or in the form of a suspension (suspension plasma spraying; SSP). In addition, the so-called SPPS process (solution precursor plasma spraying) is considered, in which the plasma flame precursor compounds for the SiO ₂ synthesis are supplied and the oxidation to SiO ₂ in the Pias- Maflannnne or takes place during deposition on the substrate body surface. In the SSP process, particularly fine particles can be used, which facilitates the production of thin layers, for example a final dense layer for sealing.

Alternatively and equally advantageously, the reflector layer is produced by flame spraying, wherein an arc or a fuel gas-oxygen flame are used as the energy carrier.

In flame spraying the temperature control is easier to set compared to plasma spraying, so that a given opacity of the reflector layer is more accurate and reproducible to comply. In addition, these methods are characterized by a low energy input into the substrate body.

It has proven useful if the SiO ₂ particles have particle sizes in the range up to a maximum of 200 μm, preferably at most 100 μm, with SiO ₂ particles having particle sizes in the range between 1 μm and 60 μm making up the largest volume fraction.

Reflector layers generally consist of several thermally sprayed layers of SiO ₂ particles. When using SiO ₂ particles with particle sizes above 200 μm, on the one hand, thin reflector layers are scarcely producible and, on the other hand, there is the risk that the particles will not be able to absorb enough energy from the energy source in the short heating time available and therefore sintering the layer is made difficult. By contrast, particles smaller than 1 μm are difficult to handle and easily clog injection, burner or other feed nozzles.

The SiO ₂ particles particularly preferably have a particle size distribution which is characterized by a D ₅₀ value of less than 50 μm, preferably less than 40 μm, particularly preferably less than 30 μm.

In view of the opacity of the reflector layer to be maintained, sintering of the SiO ₂ particles is possible without complete transparent melting together and possible sintering of the SiO ₂ particles. Lich without deformation of the substrate body to allow. Particles in the above size range show in this regard an advantageous sintering behavior. They have a high sintering activity and therefore already sinter at a comparatively low temperature, in which on the one hand by plastic deformation supported material transport processes, which could cause a particularly rapid vitrification to transparent quartz glass, not yet take place to any appreciable extent, and in which also the substrate body not or not materially affected.

In this context, it has also proved to be advantageous if the SiO ₂ particles have a multimodal particle size distribution, with a first maximum of the size distribution in the range of 2 and 6 μm and a second maximum in the range of 20 to 60 μm.

Preferably, at least one third of the SiO ₂ particles is spherical.

Because it has been shown that spherical particles contribute to the Opaksintern to a high reflection - especially in the infrared wavelength range.

In a particularly preferred variant of the method, the SiO ₂ particles are supplied to the energy carrier in the form of granules, in which the SiO ₂ particles are agglomerated into granulate particles having sizes in the range from 2 to 300 μm, but preferably less than 100 μm.

When fixed in granular form SiO ₂ -Teichen the handling, especially the supply to the energy carrier is facilitated. This is especially true for very finely divided SiO ₂ particles with particle sizes of less than 30 microns, which are particularly well suited for carrying out the method according to the invention.

Furthermore, it has proven useful if the SiO ₂ content of the SiO ₂ particles is at least 99.9% by weight.

There is no risk of contamination or crystallisation from this starting material. The content of impurities is preferably less than 1 ppm by weight. In a further preferred embodiment of the method, a reflector layer is produced with a layer thickness in the range between 50 μm and 3000 μm, preferably in the range between 100 μm and 800 μm.

The thicker the SiO ₂ reflector layer is formed, the more complete is the reflection of radiation. Additionally, in applications requiring a high density of the reflector layer - for example, to seal or avoid generation of particles from the layer - the concomitant reduced opacity of the layer may be offset by greater thickness. However, reflector layers with a layer thickness of more than 3000 μm can only be produced at great expense and, as a rule (with essentially opaque layers), the additional effect of the greater layer thickness is barely noticeable. In the case of SiO ₂ reflector layers with thicknesses below 50 μm, on the other hand, it is difficult to reproducibly adhere to a given diffuse reflection, since even small differences in the opacity of the layer have a noticeable effect on the reflectance.

Especially for the production of large layer thicknesses, a procedure is preferred in which a plurality of successive layer layers are applied for producing the reflector layer.

For the production of reflector layers with specific properties either the SiO ₂ particles are provided with a dopant, or the energy carrier is supplied in addition to the SiO ₂ particles, a dopant.

The reflector layer produced in this way contains one or more dopants which can give the reflector component an additive functionality adapted to the specific application or simplify its production. Examples of this include an adaptation of the reflection and thermal insulation by a dopant selectively absorbing in a certain wavelength range, an increase in the service life by a doping agent which increases the viscosity of quartz glass, an improvement in the chemical resistance or a reduction in the risk of contamination emanating from the component , and especially in a plasma process, the improvement of the coupling of the Plasmas by a dopant that absorbs radiation in the region of the main emission wavelength of the plasma.

A further advantageous application results when a high-temperature volatile dopant is used.

At a temperature in the range of the sintering temperature of the reflector layer or in the range of the operating temperature of the energy carrier, the volatile dopant evaporates, sublimates or releases to form or release a gas. The gas enters the reflector layer and facilitates the creation and maintenance of high opacity.

As preferred dopants, one or more of the compounds from the group: ZrO ₂ , Al ₂ O ₃ , ZrSiO ₄ , oxide carbide or nitride compounds of rare earth metals, SiC and Si ₃ N ₄ , are used.

The dopants may be evenly distributed in the layer, or they may be concentrated in separate layers, for example, in interlayers. Also layers with a concentration gradient of dopant are suitable. An addition of aluminum in the quartz glass forms in the reflector layer Al ₂ O _3, which increases the etch resistance and the temperature stability of quartz glass and thus leads to an extension of the life of the coated quartz glass component. Similarly, additions of nitrogen or carbon, which are incorporated into the quartz glass structure in the form of nitrides or carbides, provide stiffening of the glass structure and, for example, a better etch resistance. Si ₃ N ₄ can easily decompose at high temperatures and thus facilitates the setting of high opacity in the reflector layer by forming gases.

Preferably, the SiO ₂ particles are amorphous.

The use of amorphous SiO ₂ particles in the beginning reduces the risk of crystal formation during the production of the reflector layer, which can lead to rejection of the thus coated component. It has proved to be advantageous if the SiO ₂ particles are produced from silicon-containing precursor compounds, preferably from precursor compounds which additionally contain nitrogen.

Suitable starting substances for SiO ₂ -containing precursor compounds are, for example, TEOS or siloxanes. Silazanes also contain nitrogen. The incorporation of nitrogen into the quartz glass of the reflector layer increases its thermal stability and improves the etch resistance.

In view of this, a procedure is particularly preferred in which the thermal spraying in the presence of a nitrogen-containing gas, in particular in the presence of NH ₃ or N ₂ O, takes place.

The thermal spraying can be carried out, for example, by means of a plasma flame as the energy carrier and with the supply of the nitrogen-containing gas to the plasma flame. This treatment is particularly suitable as a final treatment for producing a surface layer containing nitrogen.

With regard to the quartz glass component with reflector layer, the above-stated object is achieved, starting from a component of the type mentioned in the introduction, in that the SiO ₂ reflector layer is formed as an opaque layer produced by thermal spraying.

The quartz glass component according to the invention has a completely or partially opaque reflector layer of doped or undoped quartz glass produced by thermal spraying. The opaque quartz glass acts as a diffuse optical reflector.

The component is preferably used in the process reactor, lamp and reflector manufacturing, wherein it is in the form of a tube, piston, a chamber, HaIb- shell, spherical or ellipsoidal segment, plate, a heat shield or the like. The quartz glass component is either part of an optical radiator or a heating reactor with an integrated reflector, this being formed by the SiO ₂ cover layer, or the component forms a separate reflector and is used in conjunction with an optical radiator or heating reactor. The quartz glass component is obtained by means of the method according to the invention, the reflector layer being characterized not only by its opacity but also by high adhesive strength, a high homogeneity of its optical properties, in particular the effect as a diffuse reflector, which is decisively determined by a uniform pore distribution uniformly high density and characterized by excellent chemical and thermal resistance, mechanical strength and high thermal shock resistance. Particularly noteworthy is their freedom from cracks and the even distribution of density.

It is suitable as a diffuse reflector for radiation over a wide wavelength range. The opacity of the reflector layer is shown by the fact that the direct spectral transmission in the wavelength range between 200 nm and 2500 nm is below 2%.

The SiO ₂ reflector layer is preferably made of a material of inherent material with respect to the material of the substrate body. "Arteigenheit" is understood here to mean that the SiO ₂ content of the glass composition differs from that of the substrate body by a maximum of 1% by weight, preferably by a maximum of 0.1% by weight. On the one hand, the thermal expansion coefficients between the quartz glass of the component and the reflector layer are made possible as far as possible, and thus a particularly good adhesion is achieved.

Advantageous embodiments of the quartz glass component according to the invention will become apparent from the dependent claims. Insofar as specified in the dependent claims embodiments of the component the procedures mentioned in subclaims for the method according to the invention are modeled, reference is made for supplementary explanation to the above statements on the corresponding method claims. The embodiments of the quartz glass component according to the invention mentioned in the other subclaims are explained in more detail below. In a preferred embodiment of the quartz glass component according to the invention, the substrate body is designed as a quartz glass enveloping body for receiving a radiation emitter.

In this case, the quartz glass enveloping body encloses a radiation emitter, such as a heating coil, a carbon ribbon or a radiation-emitting gas filling, and at the same time a part of the enveloping body is provided with the diffusely reflecting SiO ₂ reflector layer. The SiO ₂ cover layer is provided on the outside of the enveloping body facing away from the radiation emitter, so that impairments of the radiation emitter or of the atmosphere within the enveloping body are avoided.

The SiO ₂ reflector layer has a reflection coefficient of at least 0.6, preferably at least 0.8, in the wavelength range from 1000 nm to 2000 nm.

The reflection coefficient is understood to be the intensity ratio of the incident perpendicular to the reflector to the reflected radiation. An integrating sphere is suitable for measuring the diffusely reflected radiation.

When using high-purity, synthetic SiO ₂ Ausgangsmatehal also results in a high reflectance in the UV wavelength range.

The invention will be explained in more detail with reference to embodiments and a drawing. In the drawing shows in a schematic representation in detail:

1 shows a reactor for the treatment of wafers whose outer wall is formed by a layer of opaque quartz glass, in a view on the front side,

Figure 2 shows a cladding tube made of quartz glass for an optical radiator whose cylinder surface is covered with a reflector layer of opaque quartz glass, and Figure 3 is a reflection curve for the reflector layers shown in Figures 1 and 2.

Figure 1 shows schematically and as a longitudinal section a dome-shaped reactor 1, as it is used for etching or CVD processes in semiconductor production.

The reactor 1 consists of a dome-shaped base body 2 made of transparent quartz glass, which is provided with an outer layer 3 made of opaque quartz glass and on the underside of which a flange 5 made of opaque quartz glass is provided.

The quartz glass reactor has an outer diameter of 420 mm, a height of 800 mm and a wall thickness of 4 mm. The outer layer 3 is produced by means of thermal spraying, as will be explained in detail below. The thickness of the outer layer 3 is about 350 microns. It has a high diffuse reflection over a large wavelength range and, in contrast to gold reflector layers, it can also be used on a reactor 1 when it is inductively heated. A gold reflector layer would be destroyed by coupled energy immediately.

In this application, it is particularly important to the IR-reflective properties, because the heat should not radiate to the outside, but remain within the reactor 1, in order to reduce the energy demand and the temperature load of the surrounding equipment parts and to a homogeneous temperature distribution in the interior to reach the reactor 1.

The production of the outer layer 3 will be described in more detail by way of example with reference to the method according to the invention.

The layer substrate of the base body 2 is sandblasted and then cleaned to eliminate other surface contaminants, in particular of alkali and Erdalkakali compounds, in 30% hydrofluoric acid.

A powder of synthetic SiO _{2 is} provided which consists of spherical, amorphous SiO ₂ primary particles with an average grain size of around 50 μm. The SiO ₂ primary particles together with 2% by weight of silicon nitride powder (α- Si ₃ N ₄ ) and dispersed in demineralized water. After setting a liter weight of 1310 g and a viscosity of 150 mPas, the suspension is centrifugally atomized by means of a conventional spray dryer. In this case, a spherical SiO ₂ spray granules are obtained with a size distribution which is characterized by a D ₅₀ value of 32 microns and by a pore volume of 0.6 g / l and an average pore radius of about 20 nm. After drying at 400 ^° C., the granules are thermally consolidated by heating to 800 ^° C.

The granules are processed in a vacuum plasma spraying system with an Ar-H ₂ plasma and a plasma power of 45 kW on the base body 2 as an opaque outer layer 3. The admixed Si ₃ N ₄ decomposes into SiO ₂ and nitrogen-containing gases, which are partially enclosed in the granules and prevent the density sintering and transparency of the granules. The resulting porosity contributes significantly to the diffuse reflection of the outer layer 3 produced.

FIG. 2 schematically shows a radial cross-section of a cladding tube 20 for an excimer radiator for use in the UV wavelength range. The main emission direction of the cladding tube 20 in the embodiment downwards and is symbolized by the directional arrow 21. On the main radiation direction 21 facing away from the top 22 of the cladding tube 20, a reflector in the form of an O pakbeschichtung 23 is formed with a thickness of about 1 mm, the production of which is explained in more detail below.

The layer surface of the cladding tube 20 is sandblasted and then cleaned to remove surface contaminants, especially alkali and Erdalkakali compounds in 30% hydrofluoric acid.

A powder mixture of synthetic SiO _{2 is} provided, which is composed of spherical, amorphous SiO ₂ particles with a bimodal particle size distribution. 50 wt .-% of the powder consist of SiO ₂ particles having an average particle size of 15 microns and 50 wt .-% consist of SiO ₂ particles having an average particle size of 40 microns. The powder mixture is made by combustion flame spraying using an acetylene-oxygen combustion mixture on the top 22 of the cladding tube 20 applied as an opaque coating 23. The surface of the cladding tube is about 150 mm away from the spray nozzle.

FIG. 3 shows the reflection behavior of the diffuse reflector produced according to Example 2 (FIG. 2) in the form of an opaque SiO ₂ opaque layer in the wavelength range from 200 to 2800 nm. On the y-axis of the diagram, the reflectance "R" is in%, based on the diffuse reflection of "spectral", and plotted on the x-axis, the wavelength λ of the working radiation in nm. The reflection measurement is performed by means of an integrating sphere.

The curve 31 shows the reflection curve in the case of a 350 μm thick opaque SiO ₂ opaque layer in comparison to a 1 mm thick gold layer on a quartz glass substrate body (curve 32). It can be seen that the SiO ₂ opaque layer of undoped SiO ₂ in the wavelength range between about 200 and 2100 nm has an approximately uniform reflectance R above 80%. The diffuse reflection in this wavelength range is consistently higher than the diffuse reflection of the gold coating, as currently used (it should be noted, however, that the gold coating also produces a proportion of specular reflection). At 200 nm, the diffuse reflection of the SiO ₂ opaque layer is above the comparison standard used (Spektralon) and it is to be expected that this also applies to the even shorter wavelength VUV range. However, there is still no established method for measuring diffuse reflection in the VUV field.

This high reflection in the deep UV range opens up the possibility of using the component according to FIG. 2 for UV lamps, for example in the area of UV sterilization.

Claims

claims

1 . Method for producing a quartz glass component with reflector layer,

5 by on at least a portion of the surface of a substrate body

Quartz glass acting as a diffuse reflector reflector layer of quartz glass is generated, characterized in that the reflector layer is produced by thermal spraying by SiO ₂ particles supplied to an energy source, by means of this or melted and deposited on the sub strate body o.

2. The method according to any one of the preceding Verfahrensansprüche, characterized in that the reflector layer is produced by plasma spraying, wherein a plasma jet or a laser beam is used as the energy carrier. 5

3. The method according to claim 1, characterized in that the reflector layer is produced by flame spraying, wherein an arc or a fuel gas-oxygen flame are used as the energy carrier.

4. The method according to any one of the preceding claims, characterized in that the SiO ₂ particles have particle sizes in the range up to a maximum of 0 200 microns, preferably at most 100 microns, wherein SiO ₂ particles with

Particle sizes in the range between 1 .mu.m and 60 .mu.m account for the largest volume fraction.

5. The method according to claim 4, characterized in that the SiO ₂ - particles have a particle size distribution, which is characterized by a D ₅₀ - 5 value of less than 50 microns, preferably less than 40 microns, more preferably less than 30 microns.

6. The method according to any one of the preceding claims, characterized in that at least one third of the SiO ₂ particles is spherical.

7. The method according to any one of the preceding Verfahrensansprüche, characterized in that the SiO ₂ particles the energy carrier in the form of

Granules in which the SiO ₂ particles are agglomerated into granules having sizes in the range of 2 to 300 microns, but preferably less than 100 microns, are supplied.

8. The method according to any one of the preceding claims, characterized in that the SiO ₂ content of the SiO ₂ particles is at least 99.9 wt .-%.

9. The method according to any one of the preceding Verfahrensansprüche, characterized in that a reflector layer having a layer thickness in the range between 50 microns and 3000 microns, preferably in the range between 100 microns and 800 microns, is generated.

10.Verfahren according to any one of the preceding Verfahrensansprüche, characterized in that for producing the reflector layer a plurality of successive layer layers are applied.

11.A method according to any one of the preceding claims, characterized in that the SiO ₂ particles are provided with a dopant, or that the energy source except the amorphous SiO ₂ particles, a dopant is supplied.

12. The method according to claim 11, characterized in that a volatile at high temperature dopant is used.

13. The method of claim 11 or 12, characterized in that as a dopant, one or more of the compounds from the group of ZrO _2, Al ₂ O _3, ZrSiO _4, oxide, carbide or nitride compounds of rare earth metals, SiC and Si ₃ N ₄ , are used.

14. The method according to any one of the preceding claims, characterized in that the SiO ₂ particles are amorphous.

15. The method according to any one of the preceding claims, characterized in that the SiO ₂ particles are produced from silicon-containing precursor compounds, preferably from precursor compounds which additionally contain nitrogen.

16. The method according to any one of the preceding claims, characterized in that the thermal spraying in the presence of a nitrogen-containing gas, in particular in the presence of NH ₃ or N ₂ O, takes place.

17. quartz glass component having a reflector layer, comprising a substrate body made of quartz glass, the surface of which is at least partially occupied by an acting as a diffuse reflector SiO ₂ reflector layer, characterized in that the SiO ₂ reflector layer as produced by thermal spraying and opaque layer is trained.

18. Component according to claim 17, characterized in that the SiO ₂ content of the SiO ₂ reflector layer is at least 99.9 wt .-%.

19. Component according to claim 17 or 18, characterized in that the reflector layer has a layer thickness in the range between 50 microns and 3000 microns, preferably in the range between 100 microns and 800 microns.

20. Component according to one of claims 17 to 19, characterized in that the reflector layer is formed of a plurality of successive layer layers.

21. Component according to one of Claims 17 to 20, characterized in that the SiO ₂ reflector layer contains at least one dopant which produces optical absorption in quartz glass in the ultraviolet, visible or infrared spectral range.

22. Component according to one of claims 17 to 21, characterized the SiO ₂ reflector layer contains at least one dopant selected from the group: ZrO ₂ , Al ₂ O ₃ , ZrSiO ₄ , oxide carbide or nitride compounds of the rare earth metals, SiC and Si ₃ N ₄ .

23. Component according to claim 22, characterized in that the dopants are contained in separate layer layers or in layers having a concentration gradient of the dopant.

24. Component according to one of claims 17 to 23, characterized in that the substrate body is formed as a quartz glass enveloping body for receiving a radiation emitter.

25. Component according to one of claims 17 to 24, characterized in that the SiO ₂ reflector layer in the wavelength range of 1000 nm to 2000 nm has a reflection coefficient of at least 0.6, preferably at least 0.8.

26. Component according to one of claims 17 to 25, characterized in that the SiO ₂ reflector layer consists of synthetic SiO ₂ .

27. Component according to one of claims 17 to 26, characterized in that the SiO ₂ reflector layer contains nitrogen at least in a near-surface region.