JPH04281188A - Retainer for backing form - Google Patents

Abstract

PURPOSE:To provide a retainer for a baking form, which is capable of preventing reaction with the baking form upon baking and excellent in durability CONSTITUTION:A retainer A is employed for putting a baking form, coated with molybdenum metallizing paste, and metallizing it by baking in humidified reducing atmosphere while the retainer is formed of a molybdenum plate 1 and an alumina layer 2, formed on the whole surface of the molybdenum plate 1.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a holder for placing the moldings for firing or interposing them between the moldings for firing when firing an unfired molded body or metallizing a calcined molded body. Regarding.

0002

2. Description of the Related Art Hitherto, holders made of ceramic such as alumina or heat-resistant metals such as molybdenum have been used for firing green compacts and metallizing calcined compacts.

0003

However, the above-mentioned conventional holder has the following drawbacks. (Holder made of heat-resistant metal) The molded product for firing and the heat-resistant metal often react during firing, resulting in problems such as the fired product adhering to the holder and deterioration of the quality of the fired product. During firing, heat-resistant metals tend to undergo shape deformation such as warping. (Ceramic holder) Due to the nature of ceramic, it is easily broken by mechanical impact. In addition, it is necessary to increase the thickness to maintain strength. Since it generates gas and has a hygroscopic effect, the atmosphere inside the furnace changes, which may adversely affect the firing of the molded product. Due to the nature of ceramics, it is difficult to manufacture products with complex shapes. The purpose of the present invention is to:
To provide a holder for a molded article for firing which can prevent reaction with the molded article for firing and has excellent durability.

0004

[Means for solving the problem] In order to solve the above problem,
The present invention is a holder for holding a molded product for firing when the molded product is fired in an oxidizing or reducing atmosphere furnace, and in which a protective layer of oxide ceramic is formed on the entire surface of a heat-resistant metal base. A configuration was adopted.

[0005]

[Operation and Effects of the Invention] Since the entire surface of the heat-resistant metal base is covered with a protective layer of oxide ceramic, the molded product for firing does not react with the heat-resistant metal base during firing. For this reason, the molded article for firing can be reliably fired without causing deterioration in the quality of the fired body or adhesion to the holder. Since the brittleness of ceramic is compensated for by the heat-resistant metal base, the mechanical strength is comparable to that of the heat-resistant metal base, and the holder has excellent durability.

[0006]

Embodiment A first embodiment of the present invention will be explained based on FIGS. 1 and 2. As shown in the figure, the plate-shaped jig A consists of a molybdenum plate 1 made of heat-resistant metal (thickness 0.2 mm, short and long sides approximately 2
00, 250 mm), an alumina layer 2 serving as a protective layer is formed to a thickness of 0.4 mm.

This alumina layer 2 is formed by sandblasting the entire surface of the molybdenum plate 1 to Ra (center line average roughness) = 1.
．． Alumina ceramic (
Al2O3 99.5% by weight, balance CaO, MgO,
It is formed by spraying SiO2) by plasma spraying. Note that the thickness of the alumina layer 2 is 0.1 mm.
A range of 0.55 mm is suitable. If it is less than 0.1 mm, the effects of (a) and (b) described below will be reduced, and if it exceeds 0.55 mm, cracking or peeling will occur easily.

A second embodiment of the present invention will be explained based on FIGS. 3 to 6. As shown in the figure, the conical jig B for overlaying has a conical cylinder 3 made of molybdenum (thickness 0.2 mm,
The same alumina layer 2 as in the first embodiment is coated on the inner and outer circumferential surfaces of the upper and lower bottoms (approximately 50 mm and 80 mm in diameter) using the same method.
．． It is formed to have a thickness of 4 mm.

Next, metallizing of the object to be fired 100 using the plate-shaped jig A and the conical jig B will be explained. The object to be fired 100 has a cylindrical shape and is made of Al2 O3 92
This is a calcined compact containing CaO, SiO2, and MgO in the balance by weight. A metallizing paste (Mo) 110 is applied to the upper and lower end surfaces of this object to be fired 100 . This is placed on plate-shaped jig A (see Figure 1) or further held in conical jig B (see Figure 5), and fired in a humidified reducing atmosphere (hydrogen furnace, 1400°C x 2 hours). tens of μ by
Metallize to a thickness of m.

Next, the effects of the plate-shaped jig A and the conical jig B will be described. (A) Since the surfaces of the molybdenum plate 1 and the conical cylinder 3 are covered with the alumina layer 2, the paste 11 of the object to be fired 100
0 does not come into contact with molybdenum, and during firing, the object to be fired 100
No reaction occurs between the molybdenum plate 1 and the conical cylinder 3. Therefore, problems such as adhesion between the object to be fired 100 and the jigs A and B at the contact surfaces, failure of metallization, etc. do not occur. (a) The disadvantages of alumina that it is easy to break and the disadvantages of molybdenum that it is easy to warp can be overcome by covering the surfaces of the molybdenum plate 1 and the conical cylinder 3 with the alumina layer 2. In other words, jigs A and B have mechanical strength comparable to molybdenum, and the difference in thermal expansion between them (molybdenum; 5.1×10
-6/°C, alumina; 8.0 x 10-6/°C) makes it difficult to cause shape deformation such as warping during firing. Therefore, jigs A and B have excellent durability (more than 3 times that of molybdenum alone)
. (c) Since the walls of jigs A and B are as thin as 1 mm, they have excellent thermal efficiency. (D) Since the shape of the jig can be freely selected, firing of objects 100 to be fired of various shapes can be performed. (E) By covering the surfaces of the molybdenum plate 1 and the conical cylinder 3 with the alumina layer 2, the amount of alumina used in jigs A and B can be reduced compared to when the jigs are manufactured from alumina alone. Can be done. For this reason, jig A during firing,
Gas evolution from B is small, and no noticeable moisture absorption occurs. Therefore, the atmosphere in the furnace can be kept substantially constant, and a uniform fired body can be easily produced.

The present invention includes the following embodiments in addition to the above embodiments. a. In addition to molybdenum, the heat-resistant metal of the heat-resistant metal base is
Zirconium, vanadium, titanium, chromium, tungsten, and alloys of these with other metals (Inconel, nichrome, etc.) may also be used. b. In addition to Al2O3, the protective layer contains SiO2,
MgO, ThO2, ZrO2, BeO, Y2O3
, MgO・SiO2 , 2MgO・SiO2 , Zr
O2 ・SiO2 , 2MgO・2Al2 O3 ・5
Oxide ceramics such as SiO2, 3Al2O3.2SiO2 may also be used. c. The composition of the metallizing paste of the object to be fired 100 is as follows:
In addition to Mo, W, W-AAl2 O3, W-Al2
O3-SiO2, Mo-Al2O3, W
-Mo, W-Mo-Al2O3 may also be used.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a plate-shaped jig according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of metallizing the object to be fired using the plate-shaped jig.

FIG. 3 is a perspective view of a conical jig according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a main part of the conical jig.

FIG. 5 is an explanatory diagram of metallizing the object to be fired using the conical jig.

FIG. 6 is a sectional view of a main part of the explanatory diagram.

[Explanation of symbols]

A Plate-shaped jig (holder for molded product for firing) B Conical jig (holder for molded product for firing) 1 Molybdenum plate (heat-resistant metal base) 2 Alumina layer (protective layer) 3 Conical cylinder ( Heat-resistant metal base) 100 Object to be fired (molded object for firing)

Claims (1)

[Claims] 1. A holder for holding a molded product for firing when the molded product is fired in an oxidizing or reducing atmosphere furnace, the holder comprising a protective layer of oxide ceramic on the entire surface of a heat-resistant metal base. A holder for the formed molded product for firing.