DE10212607A1 - SiC heat treatment holder - Google Patents

Abstract

The subject of the application is a heat treatment holding device which has such a high stability and rigidity that the temporal deformation of the holding device itself and the deformation of a glass substrate due to bending during the heat treatment can be kept under control and which at the same time has an excellent thermal conductivity with which a uniform heat treatment of a glass substrate can be effectively carried out in a relatively short time and which also improves handling when applying and removing a large glass substrate. The holding device is a plate-shaped heat treatment holding device to which a glass substrate is applied when the glass substrate is subjected to a heat treatment. The main phase consists of SiC, the surface has an irregular shape, the arithmetic mean roughness of the surface Ra is 0.01 to 200 mum, and the value obtained by dividing the mean distance between convex and concave places Sm by the arithmetic mean roughness Ra ( Sm / Ra) is at most 500.

Description

The present invention relates to a plate-shaped Heat treatment holding device when applying a relatively large glass substrate, such as one Glass substrates for a flat screen, is used when it is subjected to heat treatment.

When producing a flat screen, that will be Glass substrate of the flat screen after it is printed for drying and drying subjected, in this case a plate-shaped Heat treatment holding device is needed to To set up or arrange glass substrate. As Holding device for the heat treatment of a glass So far, a holding device was made of substrate crystalline glass material used.

With a heat treatment holding device crystalline glass material was the problem, however connected that the material is difficult during a relatively short period of time, because its crystalline phase through the repeated Use changed so that it became one in the material Delay came. Because a heat treatment holding device crystalline glass material also a low Stiffness modulus of about 80 GPa, bent, if the holding devices on a multi-stage frame attached and glass substrates have been heat treated, some of the holding devices in the steps above the second stage with their middle parts down so that the treated glass substrates deformed.

Since the heat treatment holding device is made of crystalline Glass material also has a low coefficient of thermal conductivity of approximately  1 W / mK, it occurs within the holding device to a temperature distribution when the temperature increases or is lowered. And if this temperature distribution is large, it can be a heat treatment Glass substrates come to irregularities. You have to therefore take enough time to warm up and cool down, which limits treatment speed subject.

Accordingly, attempts have been made in recent years to Treatment of the glass substrate mentioned above To use heat treatment holding device, the The main phase consists of SiC and the one used to burn relatively small products such as sanitary porcelain and Tiles has been used.

A heat treatment holding device, the main phase of which is made of SiC and which has hitherto been used in applications such as the firing of sanitary porcelain and tiles, generally has an area of at most 0.7 m ² and an arithmetic mean surface roughness Ra of more than 200 μm, whereby the holding device was allowed to deform over an area of approximately 0.7 m ² by warping or the like up to 3 mm. But when the holding device is used for heat treatment of a flat screen or the like, a holding device with a larger area, a smooth surface and little deformation is required.

For example, when the size of the substrate itself is used as a holding device for heat treating a glass substrate for a plasma screen, a certain type of flat panel display, a large holding device with an area of at least 0.9 mm ² , deformation by warping or the like is all the case 1 mm permitted. In addition, the heat treatment in the contact surface between the glass substrate and the heat treatment holding device causes friction due to the different thermal expansion, so that the glass substrate could be scratched by the friction if the surface roughness of the heat treatment holding device were as high as in the past. The larger the heat treatment holding device, the clearer the occurrence of the scratches.

So that the heat treatment holding device, its main phase consists of SiC, the standards described above for the heat treatment of a glass substrate the flatness usually through a surface treatment on the surface, for example by polishing, thermal spraying, glazing or the like, be improved. If a material in which the The main phase consists of SiC, for the sole reason that To improve flatness, a polishing treatment is subjected to polishing until the surface is shiny and the surfaces roughness has become extremely low. This tendency is falling especially when Si impregnated with Si is polished, d. H. SiC, which is achieved in that a pressed body consisting of SiC particles was fired becomes, while in its pores metallic Si is impregnated.

However, if a glass substrate on a heat treatment holding device is applied for as long has been polished until the surface is shiny it doesn't just take a lot of time for the glass substrate to slide on and in the holding device Position to be brought, but can be Glass substrate also difficult from the heat treatment  Remove the holding device as the glass substrate after the Heat treatment closely to the heat treatment hold device adheres, or can by sticking damage like a during heat treatment Breakage, cracks or the like occur.

Another way to improve flatness would also be to improve the flatness by polishing, after on the surface by thermal spraying or glazing a layer of glass with matching Thermal expansion was applied. If in this case but for the sole reason of improving flatness, the polishing treatment was also carried out for as long until the surface was mirror-like, it would be too the same problems as described above.

Apart from that, the flatness can be caused by thermal Syringes are improved to close the pores Surface with a thermally sprayed film fill up, or the flatness can be adjusted by adjusting the Particle size of the raw material for thermal spraying to be controlled. If, however, for thermal spraying a raw material with a coarse particle size is used, are due to the particle size of the raw material in the thermally sprayed film creates convex spots and not only can the flatness of the surface hardly improve, but could also the glass substrate will be affected.

Since the removal of the glass substrate after the completion of the heat treatment is usually carried out by an automatic machine equipped with an adsorption device such as a suction cup or the like, the removal process must be possible using an automatic machine. If a relatively small glass substrate is applied to a heat treatment holding device with a maximum area of 0.7 m ² , the glass substrate can be removed with an automatic machine even if it adheres closely to the holding device, but there have also been cases in which the removal tiny defects occurred in the adhering part of the glass substrate.

Since a relatively large glass substrate that has to be applied to a heat treatment holding device with an area of at least 0.7 m ² exhibits a high degree of adhesion, the glass substrate cannot be removed by an automatic machine, which results in lower work efficiency. In the case of a particularly large glass substrate which has to be applied to a heat treatment holding device with an area of at least 0.9 m ² , the adhesion increases even further, so that the glass substrate can not only be removed by an automatic machine, but that serious defects such as breakage and tears also occur in the glass substrate during removal.

As a countermeasure, heat was tried to provide treatment holding device with holes, can flow through the air so the adhesion is prevented, but there is a problem than the rigidity of the holder decreases, so that the bending increases.

In view of these circumstances, the invention aims to do so ab, a heat treatment holding device available to provide such high stability and Stiffness shows that the temporal deformation the holding device itself and the deformation of a  Glass substrates due to bending during the Keeping heat treatment under control, and that excellent thermal conductivity at the same time has with which in a relatively short time effectively a uniform heat treatment of a glass substrate, and also the Handling when applying and removing a large Glass substrates improved.

To this end, the invention provides heat treatment retention device characterized in that it a plate-shaped heat treatment hold device acts when heat treating a glass substrate used to apply the glass substrate is that the main phase consists of SiC, that the The surface has an irregular shape that the arithmetic mean surface roughness of the surface Ra 0.01 to Is 200 µm and that the value which is obtained by dividing the average distance between convex and concave Set Sm by the arithmetic mean roughness Ra (Sm / Ra) is at most 500.

The values used in the invention for the "arithmetic mean roughness Ra" and the "mean Distance between convex places and concave places Sm "are defined in JIS B 0601-1994.

The heat treatment holding device according to the invention is a SiC heat treatment holding device, the main of which phase consists of SiC. Because SiC compared to crystalline Glass, widely used as a material for a holding device for heat treatment of a conventional glass substrate is used, has a high rigidity, it also occurs then when the holding devices are in a multi-stage Frame can be installed, hardly to bends and leaves  the deformation of the Glass substrate by bending the holder to keep under control. The stiffness shear module is specifically preferably at least 130 GPa, where the bend is preferably at least 200 GPa can be reduced even further.

Since the SiC holding device also has a significantly higher one Has thermal conductivity as crystalline glass, that is Temperature distribution within the holding device too with a quick warming up and cooling down low and hardly occur during the heat treatment of a glass substrate Irregularities on. The heat treatment can be therefore compared to a conventional heat treatment perform in a shorter time and more effectively. As warmth The guide number is specifically preferable to at least 80 W / mK. There the SiC holding device has no crystalline phase which is similar to a holding device crystalline glass comes to particle growth, the SiC holding device deforms itself advancing time only marginally and can over a used for a long period of time.

The invention is effective when used in a heat treatment holding device with an area of at least 0.7 m ² , on which a relatively large glass substrate is applied, in which a tiny defect can occur if it adheres closely, or only difficult to remove with an automatic machine, and it is even more effective when used in a heat treatment holder having an area of at least 0.9 m ² on which a particularly large glass substrate is applied, in which serious errors such as removal a break and cracks can occur. Such large glass substrates are mainly used in flat screens such as plasma screens, which have grown in size in recent years.

To prevent the adhesion of these glass substrates, the heat treatment holding device in this invention manufactured so that the surface is irregular Form, the arithmetic mean roughness Ra 0.01 to 200 µm, better still 0.1 to 20 µm and best 0.1 to Is 10 µm and the value which is obtained by dividing the mean distance between the convex points and the concave places Sm through the arithmetic center roughness Ra (Sm / Ra) is obtained, is a maximum of 500.

By doing so, the irregularities in the Surface so that there is a difference between the Holding device and the glass substrate tiny voids passages are created for gases such as air, which prevents mutual adhesion. In addition, the setting of such reduces Surface state of sliding the glass substrate on the Holding device by which it changes its position, and its position can be easily determined.

If the arithmetic mean roughness Ra, however contact would be less than 0.01 µm place between the glass substrate and the support device closely attached, regardless of the Value that divides the mean distance between the convex places and the concave places Sm get the arithmetic mean roughness Ra (Sm / Ra) becomes, and adheres a part to the holding device and the sticky part remains when removing the Glass substrate back on the holding device, resulting in Tiny errors occur.  

If the arithmetic mean roughness Ra at least Is 0.01 µm, the tight adherence can be between the glass substrate and the holding device and that Such small errors as mentioned above occur prevent if the value of dividing the mean distance between the convex points and the concave places Sm through the arithmetic center roughness Ra (Sm / Ra) is obtained, is a maximum of 500. By the arithmetic mean roughness Ra of the stop device surface kept at least 0.01 microns will also reduce the time it takes to Application of the glass substrate on the holding device for Positioning is needed, and can also be the Reduce the extent to which the substrate holds its position changes if the holding device during treatment is moved at low temperature.

On the other hand, if the arithmetic mean roughness Ra of Holder surface is more than 200 microns, arise from the friction between the holding device and the glass substrate to which it becomes during the heat treatment due to the different thermal expansion comes between the two parts, scratches.

If the value of dividing the mean distance between the convex places and the concave places Sm through the arithmetic mean roughness Ra (Sm / Ra) received, is over 500, also take with the Heat treatment the contact points between the Glass substrate and the holding device, being in this However, if the contact points mentioned are narrow stick together, part of the glass substrate on the Holding device adheres and the adherent part at Remove the glass substrate on the holder  remains, which leads to tiny errors. The bigger the glass substrate, the harder it is Remove glass substrate or the easier it is subject to Glass substrate defects such as breakage and tears.

The irregularities in the holder surface can be trained by the surface of the burned material by burning the as the main material containing SiC was obtained, polished and then sandblasted becomes. The arithmetic mean roughness value Ra can be by the particle size of the SiC raw to be used materials, the sandblasting material and its sandblasting pressure control. And the mean distance between the convex places and the concave places Sm can be by the particle size and the degree of crowding control using SiC particles. The degree of urgency of the SiC particles can determine the density of the compact can be set.

In the invention, the ratio of the wall thickness to the area in the holding device (wall thickness / area) is preferably 2.0 × 10 ^-6 mm ^-1 to 7.3 × 10 ^-6 mm ^-1 . If the value of this ratio is less than 2.0 × 10 ^-6 mm ^-1 , a problem may arise in that the glass substrate deforms due to excessive bending. A value above 7.3 × 10 ^-6 mm ^{- 1} is disadvantageous because then the weight increases and the heat capacity is greater than necessary, so that the equipment load increases.

It is assumed that flat screens in the Future up to 50 or 60 inches (1.27 or 1.52 m) tall will be, with the increasing size of the Screens also increase the size of the holding device  is used for the heat treatment of a glass substrate for the Flat screen is needed. If the long side and the short side of the heat treatment holding device for example 1000 mm or more or 500 mm or more should reach the wall thickness of the holding device however, be 2 to 6 mm. For reasons similar to beforehand, the glass substrate may be due to a deform too large if the wall thickness of the Holding device is less than 2 mm. And if that Wall thickness is more than 6 mm, the weight increases and the heat capacity is larger than necessary so that equipment load increases.

With a view to improving rigidity shear module and thermal conductivity preferable if the heat treatment according to the invention Holding device 5 to 50 mass% metallic Si contains. A heat treatment holding device whose Main phase consists of SiC and the a set amount contains metallic Si can be done by the following Manufacturing process: SiC powder is set into the Form brought for the holding device, and the achieved Press body is burned while in an inert gas atmosphere under reduced pressure in which metallic Si occurs, or under vacuum with metallic Si is impregnated. The metallic Si, which during the Burning melts and into the compact is impregnated, binds by filling pores SiC particles into an aggregate and compacted at the same time the compact.

The same heat treatment holding device can be used but also manufacture by the following process: SiC- Powder is previously put in the mold for holding brought device, the obtained compact  pre-baked, and this pre-baked compact is burned while under an inert gas atmosphere reduced pressure in which metallic Si occurs, or is impregnated under vacuum with metallic Si to the Compress the compact. In this manufacturing the apparent porosity of the stops can be moved Control device after firing by changing the amount of filled metallic Si is set.

Apart from this, the reactivity of a heat treatment holding device containing metallic Si with respect to a glass substrate can be reduced: from a material to be treated with heat by oxidizing the surface layer in order to form an SiO ₂ layer (glass layer) on the surface and at the same time by coating the SiC layer. Particles with the SiO ₂ layer achieve the effect of rounding off the edges of the SiC particles, which means that the glass substrate can hardly be damaged.

Since the glass layer mentioned above also differs from forms itself, if no special treatment is given, with which the glass layer is formed in advance the glass layer as soon as the holding device for Heat treatment of a glass substrate is used. However, it is preferable to heat treatment the Holding device in an oxidizing atmosphere to further increase the effect, or a layer of glass on the surface by glazing, to form thermal spraying or the like.

The invention is explained in more detail below with reference to Examples described, but not as Restriction are to be understood.

example 1

To a powder in which 50 mass% SiC particles with a average particle diameter of 100 µm, 49% by mass SiC Particles with an average particle diameter of 1 µm and 1 mass% carbon powder with a medium one Particle diameters of 1 µm were mixed Polycarboxylic acid dispersant, acrylic emulsion and one Water subjected to ion exchange treatment is added and became a plate-shaped press from this mixture body formed. After the press body overnight had been dried at 40 ° C in a dryer enough Si powder is placed on the compact to make the Fill pores in the compact, and this was 1 Hour at 1800 ° C in an Ar gas atmosphere burned under reduced pressure. After the surface of the obtained burned material with one surface had been grinded, the polished upper area using that specified in Table 1 Ejection material subjected to sandblasting and the heat treatment holding device according to Example 1 achieved that the surface roughness Ra and the middle Distance between the convex and the concave Places Sm exhibited in the same table are.

Examples 2, 3

To two batches of a powder in which 50 mass% SiC Particles with an average particle diameter of 100 µm and 50 mass% SiC particles with a medium Particle diameters of 1 µm were mixed each polycarboxylic acid dispersant, acrylic emulsion and water subjected to ion exchange treatment added and was made from each of these mixtures  plate-shaped compact formed. after the Press body overnight at 40 ° C in a dryer the compacts were held for 1 hour long burned at 2000 ° C in the Ar gas atmosphere. After this the surfaces of the fired materials obtained had been polished with a surface grinder the polished surfaces each using the in Table 1 given ejection materials of a sand subjected to radiation treatment and heat treatment Holding devices achieved according to Examples 2 and 3, the the surface roughness Ra and the mean Distance between the convex and the concave Make sms in the same table are specified.

Examples 4, 5

On the fired materials used in the process of Examples 2 and 3 described above were achieved, was in each case in the calculated amounts with which adjust the porosities to the specified values given metallic Si and this for 1 hour at 1500 ° C in the Ar gas atmosphere under reduced Pressure burned to get metallic Si into the pores impregnate. This made fired materials achieved, the apparent porosity of each in the Table 1 values were set. After this the surfaces of the fired obtained. Materials with had been polished with a surface grinder the polished surfaces each using the in Table 1 given ejection materials of a sand subjected to radiation treatment and heat treatment Holding devices achieved according to Examples 4 and 5, the the surface roughness Ra and the mean  Distance between the convex and the concave Make sms in the same table are specified.

Examples 6 to 9

To four batches of a powder in which 50% by mass of SiC Particles with an average particle diameter of 100 µm, 49 mass% SiC particles with a medium Particle diameter of 1 µm and 1 mass% carbon powder with an average particle diameter of 1 µm were mixed, polycarboxylic acid Dispersant, acrylic emulsion and an ion exchange treated water was added and was made each of these mixtures a plate-shaped compact educated. After the pressed body at 40 ° C overnight had been kept in a dryer Press body in each case in the specified size processed. Around each of the compacts was the turn after decreasing the amount, enough Si powder is given to the Fill pores in the compact, and have been For 1 hour at 1800 ° C in an Ar gas atmosphere below burned under reduced pressure. This burned them Materials obtained, the apparent porosity of each the values given in Table 1 have been set were. After the surfaces of the fired are achieved Materials have been polished with a surface grinder the polished surfaces were each under Use the emissions shown in Table 1 materials subjected to sandblasting and the Heat treatment holding devices according to Examples 6 to 9 achieved, the surface roughness Ra and the mean distance between the convex places and the concave areas Sm had in the same Table are given.  

Example 10

Having a pressed body through a working process as in Example 1 described above was dried in a dryer overnight at 40 ° C had been, the compact was set in the Size processed and was then sufficient Si powder placed on the compact to keep the pores in to fill the compact, and this was for 1 hour at 1800 ° C in an Ar gas atmosphere under reduced Pressure burned. On the surface of the achieved fired material, a glaze was applied, the Thermal expansion coefficient with that of the addressed fired material matched, and at 1200 ° C. heat treated. After the heat treatment, the upper surface with 2 to 4 µm abrasive grains SiC polished and the heat treatment holding device achieved according to Example 10, the surface roughness Ra and the mean distance between the convex locations and the concave points Sm, which are shown in Table 1 are specified.

Example 11

A burned material made by a working process as in Example 4 described above was processed to the specified size. Then it was applied to the surface by thermal spraying a mullite component applied to the heat treatment holding device according to Example 11 achieve the surface roughness Ra and the mean Distance between the convex and the concave Places Sm had, which are given in Table 1.  

Example 12

A burned material made by a working process as in Example 1 described above was processed to the specified size. Then the surface was cleaned with a surface grinder polished to match the heat treatment holding device Example 12 to achieve the surface roughness Ra and the mean distance between the convex locations and the concave points Sm, which are shown in Table 1 are specified.

Comparative Example 1

By a working method like that described above Example 3 a fired material was obtained which had a lower plate thickness than in Example 3. After the surface of the fired material obtained had been polished with a surface grinder the polished surface using the in Table 1 specified sandblasting ejection material subjected and the heat treatment holding device according to Comparative Example 1 achieved the surface roughness Ra and the mean distance between the convex Places and the concave places Sm, which in the same table are given.

Comparative Example 2

By a working method like that described above Example 4 a fired material was obtained which had a lower plate thickness than in Example 4. After the surface of the fired material obtained had been polished with a surface grinder  the polished surface using the in Table 1 specified sandblasting ejection material subjected and the heat treatment holding device according to Comparative Example 2 achieved the surface roughness Ra and the mean distance between the convex Places and the concave places Sm, which in the same table are given.

Comparative Example 3

After the surface of a fired material that by a working method like that described above Example 1 had been achieved with a surface had been grinder polished, the polished waiters surfaces lapped and the heat treatment holding device achieved according to Comparative Example 3, the surfaces roughness Ra and the mean distance between convex Locations and concave locations Sm, which in the Table 1 are given.

Comparative Example 4

On the surface of a burned material that passes through a working method like that described above Example 11 had been achieved by thermal Syringes using a raw material to thermal spraying that is 1.5 to 5 times larger than that Raw material used in Example 11 for thermal Syringes, a mullite component was applied and the Heat treatment holding device according to the comparative example 4 achieved that the surface roughness Ra and mean distance between the convex places and the concave sites Sm, which in Table 1 are specified.  

Properties of the heat treatment holding devices

The properties of the individual heat treatment holding devices of the examples and comparative examples described above, the influence of these holding devices during the heat treatment of a glass substrate and the deformation of the holding devices during the heat treatment of glass substrates were investigated. The results are shown in Table 1. In addition, as a comparative example 5, the properties and the like of a conventional heat treatment holding device made of crystalline glass material were also measured and examined. These results are also shown in this table.

As can be seen from Table 1, had the warmth treatment holding devices according to Examples 1 to 12 does not affect the glass substrates as the objects of heat treatment, but it came in the case of heat treatment holding devices according to comparative example 1, 2 and 4, in which the arithmetic mean roughness of Surface Ra was more than 200, scratches on the Glass substrate and let the heat treatment stops device in the case of the heat treatment holding device according to Comparative Example 3, in which the value which at Divide the mean distance between the convex Places and the concave places Sm by the arithmeti average roughness Ra (Sm / Ra) is obtained, more than 500 scam, difficult to remove as it is close to the glass adhered to the substrate. In addition, it happened in the case of Heat treatment holding device according to the comparative example 5, in which the holding device made of crystalline glass material existed on the holding device due to their low stiffness shear modulus to a strong one Bending and therefore warping of the glass substrate as well as at an early stage Deformation of the holding device itself.

Since the main phase of the heat treatment according to the invention Holding device consists of SiC as described, has Holding device compared to a holding device Made of crystalline glass, previously used for heat treatment of a glass substrate was used, a high Rigidity, shows excellent heat conduction and can cause the deformation of a glass substrate due to a Bending under control during heat treatment keep, while at the same time allowing, in proportion even heat in a moderately short time treatment of a glass substrate. Since the Holding device also has no crystal phase that too  leads to particle growth, the deforms Holding device only slightly and with advancing time can be used stably over a long period of time become. Because the surface roughness and the distance between the convex places and the concave places the holding device can be adjusted appropriately a glass substrate easily on the holding device position without for holes in the holder to worry, and also the glass substrate easily remove from the holder.

Claims (12)

1. Plate-shaped heat treatment holding device which is applied to a glass substrate when that Glass substrate is subjected to heat treatment which consists of the main phase of SiC, the surface one has an irregular shape, the arithmetic mean roughness the surface Ra is 0.01 to 200 µm and the value dividing the mean distance between convex places and concave places Sm through the arithmetic mean roughness value Ra (Sm / Ra) is obtained, is at most 500. 2. The heat treatment holding device according to claim 1, where the surface has an arithmetic mean roughness Ra has from 0.1 to 20 µm. 3. The heat treatment holding device according to claim 1, where the surface has an arithmetic mean roughness Ra has from 0.1 to 10 µm.   4. Heat treatment holding device according to one of claims 1 to 3, which has an area of at least 0.7 m ² . 5. Heat treatment holding device according to one of claims 1 to 3, which has an area of at least 0.9 m ² . 6. Heat treatment holding device according to one of the Claims 1 to 5, wherein the glass substrate in one Flat screen is used. 7. Heat treatment holding device according to one of the Claims 1 to 6 comprising a stiffness shear modulus of has at least 130 GPa. 8. Heat treatment holding device according to one of the Claims 1 to 6 comprising a stiffness shear modulus of has at least 200 GPa. 9. Heat treatment holding device according to one of the Claims 1 to 8, the 5 to 50 mass% metallic Si contains. 10. Heat treatment holding device according to one of claims 1 to 9, wherein the ratio of the wall thickness to the area (wall thickness / area) is 2.0 × 10 ^-6 mm ^-1 to 7.3 × 10 ^-6 mm ^-1 . 11. The heat treatment holding device according to claim 9, wherein an SiO ₂ layer is contained on the surface layer. 12. Heat treatment holding device according to one of the Claims 1 to 11, wherein the coefficient of thermal conductivity at least Is 80 W / mK.