User:Dayin123/sandbox

Diffusion bounding is a method of solid-state welding joining two different materials together (movement of atoms across the interface), including metallic and non-metallic materials. The process of diffusion uses heat and pressure, usually in controlled atmosphere, for diffusion and coalescence to occur. The process is usually approached under vacuum atmosphere. Currently, diffusion bounding method is widely used in jointing of high-strength and refractory metals in aerospace and nuclear industries.

Process:

Diffusion bounding requires the process temperature to be half of the melting temperature of the metal on the absolute scare (T = 0.5Tm). The process temperate is able to make sure a high diffusion rate between the parts to be jointed. In diffusion bounding, two parts are usually heating by furnace, induction, and electrical resistance. Vacuum or inert atmosphere is required to accomplish the diffusion bounding.

• Diffusion Bounding
  Diffusion Bounding

As a result of diffusion bounding, we would have the bounded interface which has the same physical and mechanical properties as their base material. Surface treatment including polishing, etching, and cleaning as well as diffusion pressure and temperature are important factors regarding to process of diffusion bounding. Some other factors like time of contact, thermal expansion cleanliness of raying surfaces are also contributing to the process. Since the diffusion involves into the movements of atoms among the interface, the time is relative slower than other welding methods, such as explosion welding. However, due to different requirements, some of the time interval could be accomplished in few minutes.

Benefits:

• The bounded surface have the same physical and mechanical properties as the base material. Once we have finished the jointing, we could also perform the test of the jointing materials, for example, tensile testing.
• The diffusion bounding process is able to produce a high quality joints in which case no discontinuity and porosity exists in the interface. In other words, we are able to sand, manufacturing and heat the material.
• The diffusion bounding is able to help us to build high precision components with complex shapes. Also, diffusion is flexible.
• The diffusion bounding method can be used wildly, joining either similar or dissimilar materials, and also important in processing composite materials.
• The process is not extremely hard to approach and the cost to perform the diffusion bounding is not high.
• The material under diffusion is able to reduce the plastic deformation.

Applications:

• Joining of high-‐strength and refractory metals in aerospace and nuclear industries including thermal devices, liquid rocket engines, combustion chamber.