Glass to glass sealing

In the production of products with complex shapes and high requirements, the one-time forming of glass can not meet the requirements. It is necessary to adopt various means to make the glass and glass filler be sealed to form products with complex shapes and meet the special requirements, such as the sealing of electro-optic middle and multi column exposed tubes, the sealing of electron tube shell and core column, the sealing of cathode ray tube (such as TV image tube, etc.), The seal between the protoplast and the energetic body.

The sealing between glass and glass is made of glass materials, and the chemical bonds between them are covalent mixed chemistry of ions. Based on the principle of mutual affinity of similar chemical bonds or progressive chemical bonds (similar dissolving principle), glass materials and glass materials have good properties, and mutual diffusion can be directly generated at the interface during sealing.

Methods of glass to glass sealing

Glass and glass can be sealed in the following ways.

(1) Heating direct sealing can heat the melting place of glass and glass to soften and melt magnetic state, so that they can be directly sealed together to meet the requirements of air tight sealing. The sealing methods used include large flame plus glass sealing, high induction heating sealing and flame electric field combined heating sealing.

(2) For some devices which are not suitable to be directly heated by flame, glass master batch can be used to seal the glass and glass with glass solder.

(3) When the coefficient difference between the two kinds of glass to be sealed is too large and it is not suitable to melt directly, several kinds of heat sealing methods can be used

The intermediate glass whose coefficient is between the two is melted and sealed in turn.

Heating self sealing

By heating the glass locally in a small range, the wall glass at the heating place can reach the state of loading and melting, so that the glass can be hermetically sealed.

Because the thermal conductivity of glass is small, local or small domestic heating method can be used to make the glass at the heating place reach the softened state. At this time, the glass can be sealed.

The reliability and solidity of glass and glass sealing place depend on their coefficient of thermal expansion. If the coefficient of thermal pressure of mutual sealing glass is the same or the difference is small, they can be directly sealed. Strictly speaking, not only the average coefficient of thermal base of mutual sealing glass is close, but also the whole temperature range from room temperature to annealing temperature is required, The coefficient of thermal shadow pressure should be consistent as far as possible. According to Yisuan, if the difference of the heat coefficient of Zhiai is less than 10% in the whole working temperature range, the sealing stress can be controlled within the safe range, and the good sealing place will not burst.

(1) According to the different heating methods, the sealing of glass and glass can be divided into three types, i.e. big culture heating, high induction surface heating and big initial electric field fusion heating. The different ways of temperature and time opening can be divided into three types: blanking type, butt joint type and screen cone type. The heating methods and sealing methods are different, but the working process is the same. They all go through three processes: preheating, sealing and annealing.

Fire heating glass sealing can be gas (gas, etc.) air (or oxygen) to heat our glass, complete the glass between the fusion seal.

The high induction heating seal uses the electric field induction heating to make the column and the main tube seal, which is called high seal. This kind of seal method is often used in the ferrylight type to the mouth. The glass is electrically separated, and it does not need to be heated and melted under the high electric field. Therefore, graphite is usually used as the intermediate heating body to make the glass tube and the style team add smoke seal, At high temperature, it will not be combined with the glass surface, so the processing method is convenient and the cost is low. Therefore, the mold made of stone is often used as the intermediate heating body at high frequency. During sealing, the stone is heated along the mold at high frequency to make the stone heat. The heat from the mold softens the glass. The glass tube is pressed down due to its own weight surface, and finally sealed together with the exposed seal. The shape of the sealing place mainly depends on the shape and size of the stone mold.

In the original sealing of some devices, the flame electric field combined with heating dissolving sealing adopts a high electric field sealing process

Electric seal for short). First of all, the flame is used to preheat the screen and energy body controlled at a certain distance. With the heating process, the heating flame changes from soft to hard, and the screen gradually transfers to the cone. When the sealing surface of screen and cone is heated to softening state, high voltage (about 10kV) is applied on the sealing surface to make the ions in the softened glass on the sealing surface conduct electricity. Through the movement of ions, the glass melts more evenly, which improves the sealing quality. When high pressure is applied and the sealing surface is heated by electricity to make the sealing surface melt completely, the screen moves to the vertebral body again, and then moves back. At the same time, the burner and a pair of graphite electrodes also move with the moving of the screen, making the sealing place flat and reliable.