Abstract:
The instant disclosure relates to an improved heating chamber of a heating device having a non-reactive surface layer. The heating chamber includes at least one metal layer and at least one non-reactive disposed thereon. The improved heating chamber is protected against reacting chemically during the thermal treatment process, and has better anti-corrosion capability. The heating chamber is also protected against cracking. Therefore, the service life of the heating chamber is extended. A heating device having improved heating chamber and at least one method of forming the non-reactive layer are also disclosed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The instant disclosure relates to a heating chamber having reaction preventing layer (non-reactive layer); more particularly, to an improved heating chamber having a non-reactive surface layer and a method of forming the non-reactive layer. 
         [0003]    2. Description of Related Art 
         [0004]    Industrial heating devices, such as furnaces, are equipped with internal chambers to receive objects for heat treatment. The chamber is usually made of metallic material having high temperature endurance. However, when the furnace begins to heat up, special gases may be purposely introduced into the chamber, where chemical reactions are expected to occur with the disposed objects. Being exposed to high temperature and reactant gases, the chemical reaction will inevitably occur on the inner surface of the chamber, and the chamber itself tends to be corroded and crack due to brittleness. Consequently, the service life of the chamber itself is shortened. 
         [0005]    To address the above issues, the inventor strives via industrial experience and academic research to present the instant disclosure, which can effectively improve the limitations described above. 
       SUMMARY OF THE INVENTION 
       [0006]    The instant disclosure provides an improved heating chamber having a non-reactive layer, a heating device having the improved heating chamber, and at least one method of forming the non-reactive layer. Thereby, the heating chamber can have improved anti-corrosion ability and protection against cracking Thus, a longer service life can be expected. 
         [0007]    The heating chamber comprises at least one metal layer and at least one non-reactive layer disposed thereon. 
         [0008]    The heating device comprises a main body having a heating chamber formed internally. The heating chamber includes at least one metal layer and at least one non-reactive layer disposed thereon. 
         [0009]    The method of forming the non-reactive layer has the following steps: cleaning the bonding surface of a metal layer of the heating chamber; drying the metal layer surface by forced convection; vacuuming the heating chamber; introducing reactive gases into the heating chamber; and heating reactive gases to a reactive temperature, allowing a non-reactive layer to be formed over the metal layer. 
         [0010]    An alternative method of forming the non-reactive layer has the following steps: cleaning the bonding surface of a metal layer of the heating chamber; drying the metal layer surface by forced convection; spray coating the metal layer surface with ceramic powders; and heating the chamber to a sintering temperature in forming a non-reactive layer over the metal layer. 
         [0011]    The instant disclosure has the following advantages. Namely, the presence of the non-reactive layer protects the heating chamber from reacting chemically during the thermal treatment process. The chamber can have improved anti-corrosion capability and added resistance against cracking Thus, a longer service life can be expected. 
         [0012]    In order to further appreciate the characteristics and technical contents of the instant disclosure, references are hereunder made to the detailed descriptions and appended drawings in connection with the instant disclosure. However, the appended drawings are merely shown for exemplary purposes, rather than being used to restrict the scope of the instant disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a schematic view of a heating device of the instant disclosure. 
           [0014]      FIG. 2  is a partial sectional view of a heating chamber of the heating device for a first embodiment of the instant disclosure. 
           [0015]      FIG. 3  is a partial sectional view of a heating chamber of the heating device for a second embodiment of the instant disclosure. 
           [0016]      FIG. 4  is an overview of a heating chamber of the heating device for a third embodiment of the instant disclosure. 
           [0017]      FIG. 5  is an overview of a heating chamber of the heating device for a fourth embodiment of the instant disclosure. 
           [0018]      FIG. 6  is a flow chart showing a method of forming a non-reactive layer on the inner surface of the heating chamber. 
           [0019]      FIG. 7  is a flow chart showing an alternative method of forming the non-reactive layer on the inner surface the heating chamber. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0020]    Please refer to  FIG. 1 , which shows a heating chamber having a non-reactive layer of the instant disclosure. The heating chamber can be adapted in a variety of heating devices. For explaining purposes, a box-shaped heating device is disclosed herein. The heating device having a main body  1 , a door  2 , and a heating chamber  11  formed inside the main body  1  for receiving loads to undergo thermal treatment. The door  2  is hinged on the front edge portion of the main body  1  for opening and closing the heating chamber  11 . The heating chamber  11  may be a variety of geometric shapes, including rectangular, circular, or polygonal. The heating chamber  11  can also include furnace tubes or working tubes. For the instant embodiment, the heating chamber  11  is rectangular-shaped. At least one heater (not labeled) is arranged on the main body  1  for heating. 
         [0021]    Please refer to  FIG. 2 , which shows the heating chamber  11  having at least one metal layer  111  coated with at least one non-reactive layer  112 . The metal layer  111  can be made of stainless or other metallic materials. The non-reactive layer  112  can be made of nitride, carbide, oxide, or boride. In other words, the non-reactive layer  112  may be a nitride, carbide, oxide, or a boride film. For the instant embodiment, the non-reactive layer  112  is made of titanium nitride (TiN), but is not restricted thereto. 
         [0022]    The thickness of the non-reactive layer  112  is not restricted, which can be a thin or thick film depending on the application. The non-reactive layer  112  can be coated onto the metal layer  111  by spraying, thermal spraying, plasma spraying, or physical/chemical deposition. The non-reactive layer  112  can have plate-like shape and be arranged onto the metal layer  111 . The technique of disposing the non-reactive layer  112  is not restricted. 
         [0023]    Please refer to  FIG. 3 , which shows the heating chamber  11  can further include a protecting layer  113 . The protecting layer  113  can be a glaze, which is shiny, wear-resistant, and high-temperature resistant. The protecting layer  113  is disposed on the non-reactive layer  112  and can be bonded by heat treatment. The protecting layer  113  increases the protection capability and fills any potential surface crevices of the non-reactive layer  112 . Other benefits include enhancing high-temperature resistance and anti-corrosion capability. 
         [0024]    Please refer to  FIGS. 4 and 5 , which show two embodiments of the heating chamber  11  having a tubular shape and an inverted bucket-like shape, respectively. Each heating chamber  11  has at least one metal layer  111  covered with at least one non-reactive layer  112 . 
         [0025]    Please refer to  FIG. 6 , which shows the steps of a method for forming the non-reactive layer for the heating chamber. The method mainly utilizes the chemical vapor deposition technique with the following steps (please refer to  FIGS. 1 ,  2 , and  6 ). First, use weak acid or weak base to wash and clean the bonding surface of the metal layer  111  (step S 1 ). Next, use nitrogen, argon, or dry air to dry the bonding surface by forced convection (step S 2 ). Then, the heating chamber  11  is vacuumed (step S 3 ), followed by introducing various reactive gases into the heating chamber  11  (step S 4 ). The gases include hydrogen (H 2 ), nitrogen (N 2 ), titanium tetrachloride (TiCl 4 ), and ammonia (NH 3 ). For each preceding gas, the ratio is 30˜50 vol. % for hydrogen (e.g. 35˜40 vol. %), 30˜50 vol. % for nitrogen (e.g. 35˜40 vol. %), 0.1˜5.0 vol. % for titanium tetrachloride (e.g. 0.5˜1.0 vol. %), and 1˜25 vol. % for ammonia (e.g. 5˜10 vol. %). Then, these reactive gases are heated to a reactive temperature of 600˜700 degree Celsius (step S 5 ). At this temperature, the metal layer  111  of the heating chamber  11  would react with the reactive gases in forming the titanium nitride layer, or the non-reactive layer  112 , above its surface (step S 6 ). 
         [0026]    The abovementioned steps can be completed prior to assemble the heating chamber  11  to the heating device. If such option is chosen, the vacuuming and delivering/heating of reactive gases need to be completed by other apparatuses. Alternatively, these steps can also be carried out after the heating chamber  11  has been assembled to the heating device. With such option, the procedures of vacuuming and delivering/heating of reactive gases can be done with the heating device itself. 
         [0027]    Please refer to  FIG. 7 , which explains an alternative method for forming the non-reactive layer. The method involves spray coating and sintering with the following steps (please refers to  FIGS. 1 ,  2 , and  7 ). First, use weak acid or weak base to wash and clean the bonding surface of the metal layer  111  (step S 1 ). Next, use nitrogen, argon, or dry air to dry the bonding surface by forced convection (step S 2 ). Then, ceramic powders are sprayed over the metal layer  111  of the heating chamber  11  (step S 3 ). The composition of the ceramic powders may include kaolin (5˜10 wt. %), feldspar (20˜80 wt. %), limestone (1˜40 wt. %), dolomite (1˜15 wt. %), wollastonite (5˜10 wt. %), corundum (1˜15 wt. %), and quartz (1˜50 wt. %). These ceramic raw materials are grind into fine powders and mixed uniformly. Then, the ceramic powders are heated to a sintering temperature of approximately 1000˜1400 deg. Celsius (step S 4 ). For example, the non-reactive layer  112  (glazed layer) can be formed at a sintering temperature of 1200 deg. Celsius (step S 5 ). 
         [0028]    By overlaying the metal layer  111  for the heating chamber of the heating device with the non-reactive layer, the heating chamber can be protected from chemical reaction. The anti-corrosion capability of the heating chamber is enhanced. When special gases or inert gases are introduced, the heating chamber is better protected against chemical reactions. In addition, the non-reactive layer  112  enhances the structural strength of the heating chamber by preventing the formation of cracks due to brittleness, thus a longer service life can be expected. 
         [0029]    The descriptions illustrated supra set forth simply the preferred embodiments of the instant disclosure; however, the characteristics of the instant disclosure are by no means restricted thereto. All changes, alternations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the instant disclosure delineated by the following claims.