Dissimilar connection between glass and metal welding

Glass materials are widely used because of high temperature wear resistance, corrosion resistance, insulation, oxidation resistance and other characteristics, but the low ductility and poor impact toughness of glass itself limit its application in engineering. Therefore, the glass-metal composite connector, which combines the excellent properties of glass and metal, has been widely used in microelectronic packaging, batteries, instruments, solar vacuum collector tubes, composite materials and other fields, so it is of great significance to study the sealing of glass and metal. There are many sealing methods for glass and metal, among which the most studied and mature theory is matching sealing. Matching sealing is to pre-oxidize the metal before sealing to generate a layer of oxide layer with appropriate thickness on the metal surface, then put the metal and glass in a furnace for heating and holding for a certain period of time and then cool to room temperature. However, matching sealing needs to be heated in the furnace and then cooled, so the production cycle is long. However, the laser has extremely high energy, can realize rapid heating and rapid cooling in non-contact local, and can also realize the sealing of devices with complex joint shape, so it is more and more widely used in the field of sealing. The welding of glass and metal belongs to different kinds of materials, so their welding belongs to dissimilar welding. This is why we introduce dissimilar welding. In subsequent articles, we will gradually introduce the matching sealing (welding) and laser welding of glass and metal.

What is Heterogeneous Connection

In the functional requirements or the limitations of the existing technology, it is usually difficult for us to achieve heterogeneous multi-functional engineering parts without welding (connection). Therefore, in actual production is often used in combination manufacturing and often welding (connection) this technology to achieve the purpose of design. In order to achieve different functions and effects, the different properties and functions of the material welding (connection) together, welding (connection) often become an essential process. For this reason, fully understanding and mastering this technology has become a key issue in manufacturing. Different scholars have different definitions of welding (connection) from different angles. Messler believes that "a process of manufacturing parts of different parts into a whole". According to this definition, our stacked wood, rural wooden houses and furniture all belong to the category of welding (connection). Scholars Campbell believe that "the process of combining different individual components into a whole and becoming a more complex component than a single individual, that is, assembly is also a process of welding (connection)". This definition further validates that the stacked wood is actually a dissimilar weld (join). Different scholars give different definitions, but no matter which scholar's definition, it can be clear that "welding (connection)" is first and foremost an activity or process of combining different components together to form a whole unit. The second point can be made clear that "welding (joining) is the process of combining parts or structural elements together". However, the purpose of the combination must be to achieve or achieve a function that cannot be achieved by a single component. Based on the understanding of the above definition, the following three ways can be considered as the way to achieve welding (connection):

1, mechanical connection: through the mechanical way to welding (connection);

2, chemical connection: through chemical bonding (reaction) to achieve welding (connection);

3, thermal connection: through the hot melt process to achieve welding (connection).

Why the heterogeneous connection approach: Based on the need for more options, such as light weight and high efficiency, people often connect different materials together in order to achieve multi-functional engineering structures and functions. As discussed in this topic, glass and metal welding (connection). Well-known automotive industry, aerospace industry, textile industry (metal and nameplate on clothes), tool industry, medical implants, power and marine engineering and other fields.

Application of dissimilar welding (connection)

The more common example is the Boeing 787 aircraft using composite materials as the basic material of its aircraft shell, which is composed of 20% Al, 15% Ti, 10% steel and 5% other materials. In the modern automobile industry, in order to reduce weight, there are ceramic and metal welding (connection), the beam is made of steel, and there are more parts made of aluminum alloy, such as aluminum alloy pistons and aluminum alloy engine blocks. The cars developed in EU-FP6 project use different materials such as Al, steel, Mg and glass fiber.

So what is dissimilar materials can be simply defined as "when materials or materials are combined together, it is more difficult to achieve welding (connection), and the reason why it is difficult to achieve welding (connection) is that their chemical properties or physical properties are different".

Due to the differences in chemical properties, thermal properties and physical properties (such as thermal expansion coefficient, toughness, fatigue, fracture mechanics behavior, elastic modulus, etc.) of dissimilar materials, it will not only affect the welding (connection) process, but also affect the performance of the components in service. For example, galvanic corrosion, different thermal expansion coefficients and other effects will affect the service performance of the component.

In order to solve the above problems, in the product design and welding (joining) process practice, we must fully consider and as far as possible how to solve this challenge. Scholar Messler pointed out: "in dissimilar welding (connection) must be fully reduced the difference between the two, that is, through the choice of different materials or other ways to narrow the difference between different characteristics of materials. At the same time, this increases the difficulty for the operator and the designer. Because different materials in nature, such as atomic level structure, microstructure, microstructure and performance are different. When multiple materials are combined at the same time, it becomes more difficult to reduce the difference between different materials".

Since there are many types of welding (connection), we only introduce the welding (connection) of glass and metal here, which is not related to this, so we will not introduce too much here.

Glass and metal connection, currently commonly used in four main forms:
1. Mechanical connection: This is the case with ceramic sockets commonly used in the home.
2. Use sealant or sealing strip: this is the case with the door and window glass used in the home.
3. High temperature sintering method: this is the case when we use light bulbs.
4. The laser welding method we mentioned: This is a new and advanced welding method. In the laser industry, the laser gas discharge tube has a long service life and is used to weld glass and metal by laser.