NL1026156C2 - Ceramic reflector. - Google Patents

Description

Title: Ceramic reflector The present invention relates to a ceramic reflector, in particular to a ceramic reflector for use in a lamp fixture.

Reflectors for lamp fixtures are usually made of a metal such as aluminum. For such reflectors to function properly, it is desirable that they have good thermal resistance and that the side (s) of the luminaire facing the lamp exhibit good light reflection of the desired wavelengths. Aluminum lamp fixtures can generally only be used safely for lamps with a low to medium power, and with a maximum power of about 600 W.

It is an object of the present invention to provide a new reflector, in particular a reflector suitable for use in lamp fixtures for the horticultural sector.

It has now been found that this object is achieved by a reflector 20 made of a ceramic material.

The invention thus relates to a ceramic reflector, comprising a carrier body of which at least one surface is at least partially provided with a light-reflecting ceramic cover layer.

A reflector according to the invention has good thermal properties in comparison with conventional metal fixtures. This offers advantages in particular in (glass) horticulture, since lamps with a higher power can be used and fewer lamps can suffice for the same lighting.

A reflector according to the invention has very good reflective properties. In particular, the invention provides a ceramic reflector with a total light reflection of more than 85%, preferably of at least 9026156 V ~ 2 at least 90%. A conventional aluminum reflector generally has a reflection of less than 85%.

Compared to metal reflectors, a reflector according to the invention usually has a more diffuse reflection. A simpler geometry can hereby suffice than with metal reflectors, which exhibit highly specular reflection. It is otherwise possible, if desired, to increase the degree of specular reflection, for instance by applying a suitable coating, e.g. a vanadium pentoxide coating, over the light-reflecting cover layer or over a glaze layer with which the light-reflecting cover layer can be coated.

Because of the good material properties (such as material strength), thermal properties and the light-reflecting properties, the reflector itself can serve as a luminaire for a lamp, without the need for a separate conversion. The invention thus provides, inter alia, in a lamp fixture which at least substantially consists of ceramic material. By "at least substantially" is meant here at least a fixture of which, if desired, only the fitting (s) for the lamp (s) and the channels (such as wires) for the electricity supply to the lamp consist of non-ceramic material.

A reflector according to the invention is very easy to clean.

A reflector according to the invention is very robust, and is usually less susceptible to reflection losses over time than metal reflectors, the reflection of which decreases considerably in practice through gloss losses.

A reflector according to the invention can be used in various applications and in particular offers an advantage in an application in demanding environments such as in a humid / vapor-containing environment, a warm environment, environments with highly changing temperatures, a corrosive environment and / or a dust and / or other dirt-rich environment.

1026156_ 3 t:

Partly in view of the advantages mentioned above, a reflector according to the invention is very suitable, inter alia, in one or more applications selected from photography lighting, projector lighting, ship lighting, horticultural lighting, interior lighting, outdoor lighting, street lighting, surveillance lighting, building lighting, laser applications, infrared applications, transport lighting, aircraft lighting, automotive lighting, bicycle lighting, runway lighting, industrial lighting, kitchen lighting, healthcare lighting, oven lighting, specific location lighting (such as parking places, 10 gas stations), stadium lighting, sports hall lighting, theater lighting, hall lighting, LEDs (light-emitting diodes), fume cupboard lighting, and the like.

With terms such as "about", "at least mainly", "mainly", "approx. And the like, at least a deviation of at most 5%, in particular of at most 2% is included.

Weight percentages are based on the total weight unless stated otherwise.

The carrier body is usually a ceramic material. An advantage of this is the high heat resistance compared to metals. It has thus been found that a reflector according to the invention with a ceramic support body has a very good heat resistance that allows application in, for example, luminaires where the reflector is exposed to temperatures of more than 300 ° C or even 400 ° C or more, while conventional aluminum fixtures cannot withstand 25 temperatures in excess of 300 ° C.

A white ceramic material is preferably used as the carrier body.

Preferably the material has a relatively low thermal expansion coefficient. Very suitable is, for example, a ceramic material with an expansion coefficient of less than about 6 x 10 3 K * 1, more preferably from about 3.5 x 10 4 K 1 to about 5.5 x 10 4 K -1.

Porcelain, particularly hard porcelain, is very suitable.

(Hard) porcelain has been found to have a positive influence on light reflection. In addition, the porcelain has a relatively low expansion coefficient, which has been found to be favorable in view of applications where large temperature changes occur, such as when used in luminaires for high-power lamps such as growth lamps. This is furthermore advantageous in applications in which temperature shocks can occur on the material, for example due to exposure to water. This includes spraying water in horticultural greenhouses and in general outdoor applications. Hard porcelain is also particularly suitable because of the extremely good design properties.

The terms porcelain and hard porcelain are well-known terms in the art.

In particular, the (hard) porcelain is a ceramic material that is mainly composed of aluminum oxide and silicon oxide.

The (hard) porcelain can suitably be based on a mixture of kaolin, calf feldspar and quartz. Very suitable is a (hard porcelain based on about 50 ± 5% by weight kaolin, about 25 ± 5% by weight and about 25 ± 5% by weight quartz.

Such raw materials are natural minerals and can, among other things, differ greatly in mineralogical and chemical structure. The quality of the raw materials is partly determined by the purity, in particular with regard to the degree of absence of coloring elements such as Fe 2 O 3, MnO 2, Cr 2 O 3, TiO 2 (in combination with, for example, Fe 2 O 3). The person skilled in the art will be able to choose suitable recipes on the basis of the raw materials used and process conditions (such as fire curves furnaces). Hard porcelain is preferably chosen to be a porcelain that has been baked at a top temperature of about 1380-1420 ° C.

1026156 _ 5

The specific gravity of a very suitable (hard) porcelain is approximately 2.4-2.7 g / cm 2.

Hard porcelain with a hardness (Mohs) of 7-9 is particularly suitable.

Hard porcelain is generally at least substantially free of open pores. In particular, the open porosity is so low that the saturation moisture absorption (at approximately 25 ° C) is less than 0.1 wt. % based on the weight of the reflector.

As starting material for the light-reflecting cover layer, a light-reflecting ceramic material is usually used. Suitable materials include calcium pyrophosphates, barium sulfates, magnesium oxides, titanium dioxides and alumino silicates (oxides containing mainly silicon and aluminum in addition to oxygen). These can be used alone or in any combination.

The light-reflecting ceramic material preferably has a relatively low expansion coefficient, in particular of less than about 6x10-6 K * 1, more in particular of less than about 5x10-6 K * 1

Preferably, the reflective cover layer has an expansion coefficient that is approximately equal to or lower than the expansion coefficient of the body 20 on which the cover layer is applied.

Very good results have been obtained with a reflector in which the ratio of the thermal expansion coefficient of the support body to the thermal expansion coefficient of the light-reflecting ceramic cover layer is at least about 1, more preferably at least about 1.1. The ratio of the coefficient of thermal expansion of the support body to the coefficient of thermal expansion of the light-reflecting ceramic cover layer is preferably at most 1.5, more preferably at most 1.4, very most preferably at most about 1.25.

Such a reflector has been found to be extremely resistant to temperature shocks.

1026156 6

More preferably, the expansion coefficient of the light-reflecting cover layer is 0 to about 1 x 10 * 6 K'1 lower than the coefficient of expansion of the support body. Very good results have been achieved with a reflector with a light-reflecting cover layer whose expansion coefficient 5 is approximately 0.5 χΙΟ -6 K * 1 to approximately 1 x 10 K 2 K * 1 lower than the coefficient of expansion of the carrier body

Very good results in this regard have been obtained with a reflective coating of an aluminosilicate, in particular in the case where the body comprises a (hard) porcelain material. It has been found that with this a reflection of white light of 93% and more is achievable.

Preferably, the light-reflecting cover layer (and optionally the support body) comprises an aluminosilicate with an Al2O3 to S1O2 molecular ratio of about 3: 2. Preferred weight percentages for these oxides are shown in Table 2b (see Example 1).

Examples of particularly suitable aluminosilicates for use in the reflective coating are mullite and zirconium mullite. Mullite is an inorganic oxide with the gross formula 3Al20s.Si02. Zirconium mullite is an inorganic oxide based on oxides of zirconium, aluminum and silicon. ZrO 2 is usually present herein at a level of about 34-38 wt. %, Al 2 O 3 at a level of about 43.8-47.8 wt. % and S102 in a content of approximately 16.5-18.5 wt. %.

More preferably, the light-reflecting cover layer consists at least substantially of sintered mullite. It has been found that it exhibits a very good reflection for light. It has further been found that a cover layer of mullite 25 is very suitable for the manufacture of a reflector which is highly resistant to temperature changes.

Another reflective ceramic material is alumina. However, alumina has been found to be less suitable for use in ceramic reflectors for high-power lamps than an aluminosilicate. Namely, it has been found that the durability of the reflective cover layer 1026156 7 is relatively low and already starts to show cracks after relatively short heating by exposure, in comparison with an aluminosilicate cover layer.

It is possible to use formulations in which, in addition to mullite or another ceramic light-reflecting material, one or more substances have been added which reduce the transparency of the cover layer and / or contribute to the reflection of light. For example, the reflected intensity can be adjusted.

The reflection of light can for example be improved with an additive selected from the group of zirconium, tin oxide and cerium oxide, in particular in an aluminosilicate coating.

The thickness of the cover layer can easily be determined experimentally, depending on the desired reflection properties, commercial considerations and the like.

Partly for commercial reasons (the material for the cover layer is usually relatively expensive), the average thickness of the reflective cover layer is preferably less than about 1.5 mm, more preferably less than 0.7 mm.

In view of high reflection, the layer thickness is preferably at least about 100 µm.

Very good results have been obtained with an average layer thickness in the range of 100 * 500 μχα.

If desired, a glaze layer has been applied over the light-reflecting cover layer. A glaze layer contributes to the smoothness of the surface and simplifies the cleaning of a reflector.

Such a layer is particularly desirable in an embodiment in which the assembly of carrier body and light-reflecting cover layer is open-porous, more particularly in the case that the open-porosity is such that the saturation of moisture (at approximately 25 ° C) ) more than 0.1 wt. % based on the weight of the reflector.

1026.15 β I

8

The glaze layer can be based on the usual materials, for glazing ceramic, in particular for glazing porcelain. Very suitable are glaze layers based on an aluminosilicate.

With regard to the thermal expansion coefficient of a preferred glaze layers, the same considerations apply here as for the light-reflecting cover layer (see above).

The glaze layer can be transparent or opaque. In the case of an opaque glaze layer, the glaze layer can be applied to a light-reflecting cover layer or itself serve as a light-reflecting cover layer and optionally be applied directly to the support body, without intermediate light-reflecting layer.

An opaque enamel layer preferably comprises one or more opacifying agents, preferably selected from the group consisting of tin oxide, cerium oxide or zirconium oxide. An advantage of an opaque enamel layer, in addition to the aforementioned advantages of enamel layers in general, is that it can contribute to the reflection or even completely serve as the light-reflecting cover layer.

The thickness of the glaze layer can be chosen within wide limits. Good results have been obtained inter alia with an average glaze layer thickness of 400 µm or less (in combination with a separate light-reflecting cover layer) or with an average layer thickness as specified for the light-reflecting cover layer (when the glaze is applied directly to the support body and no separate reflective cover layer is present. For practical reasons, the glaze layer is preferably at least about 100 µm, if present.

To increase specular reflection, a (top) layer can be applied to the glaze layer that improves specular properties. Very suitable for this is a layer on hasie of vanadium pentoxide. Such a layer has been found to contribute to very good specular 1026156 9 properties of the reflector. A specular reflection enhancing layer with a thickness of approximately 10-100 µm is very suitable

The surface of a reflector according to the invention can be uniform, that is to say consist of one type of material. It is also possible to provide a multiform surface. i.e. a surface that is made up of different types of materials next to each other, and / or over each other. For example, the surface of a reflector according to the invention can be constructed from different types of material, which can be arranged next to each other and / or over each other, with possibly different light-reflecting properties. Thus, the ratio of specular / diffuse reflection can be adjusted, the total degree of reflection and / or the reflection pattern. The surface can be formed, for example, by different types of materials selected from transparent glaze, opaque glaze, light-reflecting material (such as mullite), specular-reflecting material (such as vanadium oxide) and the like.

The invention furthermore relates to a method for manufacturing a ceramic reflector, such as a reflector described above, comprising - applying a suspension of a light-reflecting material to a support body; and then sintering the applied suspension to form a light-reflecting coating.

More preferably, the carrier body (with possibly one or more other layers already applied to it) is exposed at least at a given moment to a sintering temperature of approximately 1400 ° C, more in particular to a sintering temperature of approximately 1380-1420 ° C. This is particularly advantageous for obtaining hard porcelain.

Figure 1 shows seven preferred processes (processes A-G).

The carrier body, such as a (hard) porcelain body (or a precursor material thereof that is transformed into (hard) porcelain during the process) can be obtained in any way. The material can for example be burned in a conventional manner.

Good results have been obtained with a carrier body obtained by a sponge fire at about 1000-1420 ° C (top-5 temperature).

The carrier body can be sintered before, during or after the application of the cover layer, more preferably at a temperature of about 1380-1420 ° C (top temperature), which temperature is particularly suitable for obtaining a hard porcelain carrier body.

The suspension can be obtained by mixing the ingredients in a conventional manner. A water-based suspension is usually used.

As a light-reflecting material, such as the mullite or another aluminosilicate, a starting material is usually chosen which consists mainly of microparticles (i.e. particles with a diameter of less than 1000 μπι). The material preferably consists at least substantially of relatively small microparticles, in particular at least substantially of particles with a diameter of less than 50 µm.

It has been found that shrinkage behavior during sintering and reflective properties of the sintered light-reflecting cover layer can be adjusted, inter alia, by the choice of the particle size distribution of the light-reflecting starting material.

The light-reflecting material preferably (at least before sintering) has a particle size distribution in which at least 90% of the particles, preferably at least 95% of the particles have a diameter of less than about 50 μιη

Preferably, at least 50% of the particles have a diameter of less than about 25 μιη.

Preferably at least 25% of the particles have a diameter of at least about 1 μπι.

> 026156 ____________ 11

Very good results have been achieved with a light-reflecting material, in particular mullite, of which at least 95% of the particles have a diameter of at most 40 μχη, 15 to 75% of the particles have a diameter of at most 25 μιη and 1 to 50% of the particles has a diameter of less than 1 μχη.

The particle sizes specified herein are based on values that are available as determined on a Coulter particle size counter.

In addition to the reflective material (usually in powder form, for mixing), one or more additives may be added to the suspension.

For example, a reflection-enhancing additive can be added as already mentioned above.

Preferably, the suspension also contains one or more sintering aids. Quantity and nature Of these materials, it is determined by the application method and in particular at which temperature the suspension is sintered on the support.

Very suitable sintering aids are zeolites, sodium alumininium silicates, potassium aluminum silicates, alkaline earth aluminum silicates, aluminum boron silicates, magnesium silicates and (complex) synthetic glass frits, such as complex compounds of alkalis, alkaline earths, lead, strontium, magnesium, etc. herein is meant a compound comprising various metal ions.

One or more of the sintering aids and / or reflection enhancing * aggregates can also be used to influence the expansion coefficient. A tension-free adhesion can thus be achieved between the light-reflecting cover layer and the carrier. $

Other properties of the suspension and / or the final light-reflecting cover layer can also be adjusted with additives, in particular additives for modifying a property selected from the group consisting of viscosity, rheology, suction behavior on the body, flow behavior, spraying behavior and mixing behavior. . Such additives are known per se for use in ceramics. The skilled person will know how to choose suitable substances.

A polyglycol or a carboxymethyl cellulose, for example, is very suitable. They have also been found to contribute to good adhesion and wiping resistance after drying the suspension.

The application can be effected in a known manner, for example by immersing or spraying. The application preferably takes place after the biscuit burning of the carrier (such as the (hard) porcelain).

The suspension is applied in an amount corresponding to the desired final layer thickness of the sintered reflective cover layer.

The suspension is then sintered at a suitable temperature. In principle, the conditions can be chosen within broad limits. The person skilled in the art will be able to choose suitable conditions depending on the desired porosity and the choice of the light-reflecting cover layer. Very suitable is a temperature in the range of about 1000-1420 ° C, in particular for sintering a suspension with an aluminosilicate as reflective material.

->

The person skilled in the art knows how to adjust the porosity, for example on the basis of the sintering temperature and / or by using one or more sintering aids. To obtain a layer of porous (or non-open-porous) light-reflecting cover layer, a relatively high sintering temperature can be selected and / or use can be made of one or more sintering aids. To obtain a very high porous light-reflecting cover layer, a relatively low sintering temperature will generally be chosen

A porous support body, as a semi-finished product, is preferably used for the manufacture of a reflector with a glaze layer. It has been found that the glaze layer adheres very well to a porous support body (whether or not provided with a separate light-reflecting cover layer. To obtain a reflector with a low porosity (of the support body) /

V

After applying the glaze layer, it is preferable to sinter at a high temperature (such as about 1380-1420 ° C to obtain hard porcelain). An example of a suitable process is indicated in Figure 1D.

Those skilled in the art will know suitable conditions for applying the glaze layer, depending on the materials used, the desired properties and what is described in the present description.

Furthermore, it has been found that the sintering temperature influences the reflection properties. In particular for coatings based on an alumino silicate, very good reflective properties have been obtained with a light-reflecting coating formed by sintering at a temperature in the range of approximately 1200-1350 ° C, such as at approximately 1300 ° C.

After sintering the reflective cover layer, an enamel layer can be applied if desired, which can then be burned down.

Suitable techniques for this are known per se. Very suitable is smooth burning at approximately 1200-1350 ° C. Such a treatment is particularly suitable for an aluminosilicate.

A layer for improving specular properties can be applied over the glaze layer, for example a layer with vanadium pentoxide, after which another temperature treatment, for example at approximately 1200-1350 ° C, can take place.

It has been found that by means of the invention ceramic reflectors can be manufactured with very high reflections and good thermal properties, which are not or at least less easily realized with other reflectors for lamp annatures. Furthermore, it has been found that a ceramic reflector has good mechanical properties. The invention therefore also relates to a reflector obtainable by a method according to the invention.

The invention also relates to a lamp fixture 30 comprising a reflector according to the invention. At least during use, a luminaire according to the invention also comprises a lamp, such as a growing lamp for growing plants, for example in the greenhouse horticulture,

Particularly good results have been obtained with a lamp with a power of more than 600 W.

The invention furthermore relates to the use of a reflector or luminaire according to the invention in street lighting.

By means of the invention, street lighting can be offered with high intensity. This is, among other things, interesting with regard to street safety.

The invention will now be further illustrated with reference to a number of examples.

1026156 15

Example 1: preferred formulations Table 1: Carrier body (hard porcelain

Preferred

Chemical composition %

General SiQ2-066-72 A12Q3 23-27

Fe2Q3 <1.0

TiQ2 <0.5

Na2Q 0-1 K2Q 2.5-4.5

CaO <0.5

MgO <0.5 5

Chemical composition Example! (measured)% weight% 1

Standard type 1 SiQ2 69 A12Q3 ~ 26

Fe 2 Q 3 0.5

TiQ2 0.1

Na 2 Q 0.1 K 2 Q 4

CaO0.1

MgO 0.2 __ total__100

Example!

Chemical composition %

Standard type 2 (measured) SiQ2__72 A12Q3 24

Fe 2 Q 3 0.4

TiQ2 0.0

Na 2 Q 0.5 K 2 Q 3

CaO 0.2

MgO__0.1 ___total 100.2! | 1026156 16

Table 2: suspension for reflective coating

Table 2a: ceramic materials and sintering agent

I J

preferred example

Recipe example (parts by weight) (parts by weight).

i light-reflecting mullite (particle size of material_ at least 90% <50 μιη) __ 75-95__87 sintering aid synthetic sodium medium_aluminum silicate__0-25__11 synthetic magnesium sintering aid silicate agent _-___ 0-15__2_ total _ [(dry inorganic substance) 100 100

A suspension is usually obtained by mixing 100 parts by weight of dry inorganic substance (light-reflecting material plus optionally sintering aid) with 20-60 parts by weight of water and 20-60 parts by weight of additives.

In the examples described below, 42.8 parts by weight of water and 36.7 parts by weight of polyglycols were added.

Table 2b Composition of coating after sintering (Preferred and in Example 21 component (Example) __ Preferred% wt. 6.0__2.6 _K20__0 ^ 0__0.01 _CaO__0-2.0__0.02

MgO, 0-2.0 0.3 1026156 17

Table 3: transparent elacid layer chemical Preference Example 2 composition ___ (wt% __ wt%

SiO2 72-74 73 A1203 11.5-13.5_13

Fe 2 O 3 __ <05_OJ.

TiO2 ≤ <05_0.05

Na2 O0-1 0.3 K2 O1.5-3.5-2.5

CaO__6JO_8j9

MgO 1.5-51 551 Example 2: preparation of an alumino-silicate reflector

A number of ceramic support bodies in the form of a test plate (80 x 80 mm) were conventionally manufactured from a porcelain standard type 1 (ST 1) and from a porcelain standard type 2 (ST 2), with a composition as shown in Table 1 ).

Example 2a: an porous support

A portion of the support bodies were spouted at about 1000 ° C, which resulted in an open-porous support. After the biscuit burning, the suspension (as shown in Table 2) was applied. The amount applied was approximately 10.5 g / dm 2. A portion of the carrier bodies was sintered at 1000 ° C, then glazed and then fired at 1400 ° C; another part was sintered at 1400 ° C and not provided with a glaze layer; yet another part was sintered at 1400 ° C, glazed and 1026150 '18 subsequently burned to the surface at 1200 or 1350 ° C. In Figure 1, suitable processes are shown in block diagrams.

The reflectors showed a reflection for white light of 93% or more. They did not show any visible cracks in the coating after prolonged exposure to varying temperatures between room temperature and a temperature of 400 ° C or more.

A reflector of up to 97% was measured without a glaze layer of a reflector whose cover layer was sintered at 1300 ° C.

Example 2b: non-non-porous carrier

The remaining carrier bodies were sponge burned at ca. 1400 ° C to form a carrier free of open pores (saturation moisture absorption <0.1%). The suspension was applied as described under Example 2a. Sintering was then carried out at 1100 ° C, 1300 ° C or 1400 ° C. A part of the reflective layers was then provided with a glaze layer that was burnt to the surface at 1200 - 1350 ° C.

The reflectors showed a reflection for white light of 93% or more. They did not show any visible cracks in the coating after prolonged exposure to varying temperatures between room temperature and a temperature of 400 ° C or more.

1026156

Claims (21)

1. Ceramic reflector, comprising a carrier body of which at least one surface is at least partially provided with at least one light-reflecting ceramic cover layer. Ceramic reflector according to claim 1, wherein the support body is made of porcelain, preferably hard porcelain. Ceramic reflector according to one of the preceding claims, the reflective layer of which has a total light reflection of more than 85%, preferably of at least 90%. 4. A ceramic reflector according to any one of the preceding claims, wherein the light-reflecting cover layer comprises a calcium pyrophosphate, a barium sulfate, a magnesium oxide, a titanium dioxide, an alumino-silicate or a combination of one or more of these compounds. 5. A ceramic reflector according to any one of the preceding claims, wherein the light-reflecting cover layer comprises sintered mullite. Ceramic reflector according to one of the preceding claims, provided with a glaze layer which is applied to the light-reflecting cover layer on the side remote from the support body. 25 Ceramic reflector according to one of the preceding claims, in which the support body, the light-reflecting cover layer and, if desired, the glaze layer all comprise ahimino silicates. Ceramic reflector according to one of the preceding claims, in which the reflective coating comprises an aluminosilicate whose molecular ratio Al2O3 to S1O2 in the aluminum silicate is approximately 3: 2. Ceramic reflector according to one of the preceding claims, in which the ratio of the thermal expansion coefficient of the support body to the thermal expansion coefficient of the light-reflecting ceramic cover layer and / or the ratio of the thermal expansion coefficient of the support body to the thermal expansion coefficient of the glaze layer is at least about 1, preferably 1-1.5, more preferably 1.1-1.4. A method for manufacturing a ceramic reflector, optionally a reflector according to any of the preceding claims, comprising 15. applying a suspension of a light-reflecting ceramic material to a support body; and then - sintering the applied suspension to form a light-reflecting coating. A method according to claim 10, wherein the sintering takes place at a temperature in the range of 1000 to 1420 ° C, preferably at a temperature of 1200-1350 ° C. 12. Method as claimed in any of the claims 10 or 11, wherein the suspension comprises an additive, preferably an additive for modifying a suspension property selected from the group consisting of viscosity, rheology, suction behavior on the body, flow behavior, spray behavior and segregation behavior. 1020156 A method according to any one of the claims, wherein the suspension is applied by immersion and / or spraying. A method according to any of claims 10 13, wherein the suspension comprises at least one sintering agent, preferably at least one sintering agent selected from the group consisting of zeolites, magnesium silicates, sodium alumninium silicates, potassium aluminum silicates, alkaline earth aluminum silicates , aluminum boron silicates and (complex) synthetic glass frits 10 A method according to any of claims 10-14, wherein at least 90% of the particles of the light-reflecting material (at least before sintering) has a size of less than 50 μια. A reflector obtainable by a method according to any of claims 10 to 15 17. A lamp fitting comprising a reflector according to any one of claims 1-10 or 16. 20 A lamp fixture according to claim 17, provided with a lamp, preferably a grow lamp. 19. Lamp fitting as claimed in claim 18, which consists at least substantially of ceramic material. A street lamp comprising a reflector or a lamp fixture according to any of claims 1-10,16 or 17-19. 10261 5 6 ·: 21. Use of a reflector according to claims 1-10 or 16 or a lamp fixture according to any of claims 17-19 in an application selected from photography, projector lighting, ship lighting, horticultural lighting, interior lighting, outdoor lighting, street lighting, surveillance lighting, building lighting, laser applications , infrared applications, means of transport lighting (such as aircraft lighting, automobile lighting, bicycle lighting, train lighting), runway and airport lighting, industrial lighting, warehouse lighting, kitchen lighting, healthcare lighting, oven lighting, specific location lighting (such as parking places, gas stations, train stations, shopping centers, terminals), stadium lighting, ( sports) hall lighting, theater lighting, hall lighting, LEDs (Light Emission Diodes) and fume cupboard lighting. 15 10 ^ 6156_