JPS5922149B2 - Ceramic firing containers containing lead - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic firing container containing lead Pb.

P9ium titanate BaTi03 and lead titanate PbTi0
3 or a mixture of PbTiO8 and lead zirconate PbZr03
Ceramics, such as PbO-containing oxides mixed with a binder and fired in a firing container, are used for ceramics such as PbO-containing oxides mixed with a binder and then fired in a firing container. Attempts have been made to appropriately adjust the amount of PbO added, since it greatly affects the physical and electrical characteristics.

However, since PbO easily evaporates during firing, even if the amount added is adjusted, the force that causes the concentration in the element body to be uneven, and the evaporation of PbO may cause pores to occur in the sintered body, resulting in a dense sintered body. It was difficult to obtain. In addition, in order to prevent additives from volatilizing during firing, conventional firing containers have a structure in which the container body 1 is sealed with a lid 2 as shown in Figure 1. Binder, moisture, and Co2 gas are not released sufficiently.

Therefore, when high concentration and sealed firing are required,
As shown in FIG. 2, a container is prepared in which a gap 3 is provided between the container body IA and the lid 2A, and the gas is released by primary firing at a relatively low temperature using this container, and then the gas is released as shown in FIG. A two-step process of high-temperature firing in a closed container was required. This increases the number of firing steps, and there is a problem in that changes in atmosphere and temperature caused by transferring the firing element have an adverse effect on firing. The present invention has been made in view of the above-mentioned circumstances, and in the firing of ceramics containing PbO, a single firing container is used and is kept open to the outside in a relatively low temperature region to release evaporative gases such as binder. The purpose of the present invention is to provide a one-step firing container that is sealed in a high-temperature region and forms a PbO atmosphere inside the container to prevent volatilization of elemental additives. .

Figure 3 is a side sectional view A and a side sectional view B showing an embodiment of the present invention.
It is.

The lower container I vessel 4 having a square plane or a round plane has several element bodies 5 on the inner bottom surface, and fired element bodies T containing PbO are placed on these several bodies 5 via a bedding powder 6. The lower container 4 has a stepped fitting portion 4A that fits into the side wall stepped fitting portion 8A of the upper container 8 as a lid, and the stepped portions of the fitting portion 8A and the fitting portion 4A are projected. - They are mated together and become a sheath. An evaporative substance 9 containing PbO, such as PbO alone or PbCO, which evaporates during high-temperature firing, is provided at the abutting portion of the fitting portion 4A of the lower container 4 and the fitting portion 8A of the upper container 8. This evaporated substance 9
The stepped fitting part 4A of the lower container 4 allows the evaporation of
A vent hole 10 is provided in the. Further, the stepped fitting part 8A of the upper container 8 has a recess facing the sliding part with the fitting part 4A, and this recess contains the same evaporative substance 11 as the evaporative substance 9. A vent hole 12 is provided in the stepped fitting portion 4A of the lower container 4 so that the vapor 11 also evaporates into the container. These evaporated substances 9
, 11 are provided at least at the four corners if the container is square, or are arranged in an appropriate number such as at least three equally spaced if the container is cylindrical. Further, vent holes 10 and 11 are arranged in a distributed manner in the fitting portion 4A of the lower container 4 in correspondence with the evaporated substances 9 and 11. When the upper container 8 is in a state of being fitted into the lower container 4 via the evaporative substance 9, there are a plurality of vent holes 8B on the circumferential surface facing the end surface of the fitting part 4A of the lower container 4 and communicating with the inside of the container. provided. This vent hole 8B faces the side of the stepped fitting portion 4A and is closed when the upper container 82 is lowered to the lower container side due to evaporation of the evaporative substance 9 or by an external pressing force. Therefore, at least the dimension a of the vaporized substance 9 is made larger than the dimension b of the vent 8b. The evaporative substances 9 and 11 may be powders or those press-molded at a pressure lower than the molding pressure of the element body, or a mixture of PbO and ZrO, which does not evaporate, so that it remains when PbO evaporates. The amount of evaporation of PbO can also be controlled by changing the amount of ZrO. In this case, ZrO, dimension A according to the amount
, b. Further, the number and amount of evaporated substances to be installed are determined by the number and volume of the element bodies 7 to be stored in the container, and the amount of additive PbO. In such a configuration, the evaporated substances 9,1
1 begins to evaporate at a temperature of approximately 600°C and becomes extremely active at 1000°C. Therefore, in a low temperature range (for example, 500° C.) below the evaporation temperature of the evaporative substances 9 and 11, ventilation inside and outside the container is ensured when the upper container 8 is supported by the evaporative substance 9 in the state shown in FIG. When the temperature rises to 500° C., moisture in the fired body 7, gas generated by decomposition of the binder, etc. are vented to the outside of the container through the vent 8B. Thereafter, for firing in a high temperature region at or above the evaporation temperature of the evaporative substances 9 and 11, the upper container 8 is lowered by the evaporation of the evaporative substances 9, and its vent port 8B is closed, resulting in a sealed state. Therefore, inside the container, PbO from the evaporated material evaporates as well as the evaporated material.
The PbO is filled with the volatilization of PbO, and firing is performed in which volatilization of PbO from the element body 7 is prevented. As described above, according to the present invention, vents are formed inside and outside the container during low-temperature firing by allowing evaporated substances to pass between the lower container of the container for storing the fired element and the upper container serving as its lid. , during high-temperature firing, the evaporated material is evaporated, and the vent is closed and the evaporated material is evaporated.
By using a substance containing bO, it is possible to perform firing with the vessel filled with PbO, which causes the release of binder gas and other gases that adversely affect the porosity of the element body during firing at low temperatures, and the addition of PbO as an additive during high-temperature firing. It is possible to perform continuous firing in one step using one container, which can produce a uniform sintered body with suppressed volatilization.

In addition, in the embodiment, a case was shown in which a substance 9 which also had the function of controlling the lowering of the upper container and a substance 11 for mere evaporation in the vessel were provided as evaporative substances, but this evaporative substance 11 was not allowed to evaporate in stages when the container was sealed. The PbO inside the container is configured to be located at the vent 12 position of the fitting part 4A and volatilized into the container after being sealed.
The amount can be controlled reliably, and the amount of harmful PbO emitted outside the container before sealing can be reduced.

In addition, the evaporative substances 9 and 11 are not limited to being provided in the upper container, and the design can be changed as appropriate, such as by reversing the way they fit with the lower container.

[Brief explanation of the drawing]

Figures 1 and 2 are side views showing a conventional firing container;
Figures A and B are a side sectional view and a side view showing one embodiment of the present invention. 4...Lower container, 7...Sintered element body, 8...Upper container,
9,11...Evaporation substance, 8B,10,12...Vent.

Claims (1)

[Claims] 1. In a firing container that houses a fired element containing lead and is used for firing in a sealed state, the fired element is placed on the inner bottom surface and has a fitting part on the side wall, a lower container; ,
a lower container that fits into the fitting portion of the lower container and has a side wall portion with a ventilation hole to cover the upper portion of the lower container; Then, a predetermined gap is provided to form ventilation between the firing element body and the outside air through the ventilation hole, and in the high temperature firing area, the air evaporates into the container and there is no gap between the upper and lower containers. 1. A firing container for ceramics containing lead, characterized in that it is equipped with an evaporative substance containing lead to close the vent hole and bring the airtight airtight into a sealed state.