Room Temperature Bonding

Room temperature bonding is the technology which joins substances together under normal temperature. Although the power to mutually adhere (intermolecular force) exists on the substance surface, this power is usually affected by surface unevenness, the layer of oxygen, etc., and substances cannot joined simply by overlapping them.

We are in the practical use stage for room temperature bonding using highly precise polishing. It enables tricky bonding between sapphire parts or sapphire and different materials such as metal and glass. It effectively eliminates O-ring or screw fastening to realize a simple and ideal window structure without any point of deterioration that has to be maintained. Furthermore, the technology can tightly connect two materials with different thermal expansion coefficients, which may be difficult to achieve with brazing. Also, parts for which heat deformation is a concern, or even coated surfaces that have a low resistance to high temperatures, can be bonded together. This developing technology may carry hidden potential to be applied in broad range of fields, such as industrial window components like sensor covers, or exterior parts for jewelry that require flexible designs.

Features of room temperature bonding technology

Bonding can be done at room temperature

Sapphire parts can be bonded both to sapphire as well as to different materials

Bonding in the atmosphere is possible

- Bonding is possible even in the atmosphere since the Au coated surface is still activated there.

The bonding process: bonding in the atmosphere using Au film

High corrosion resistance and airtightness

Low number of parts

View port example (Sapphire and aluminum)
More simplified structure without O-ring is possible.

No adhesive is used

Expected applications for room temperature bonding

  • Various kinds of view ports
  • Sapphire window with flange
  • UV/IR transmission window
  • Sensor cover
  • Observing cell
  • Crystal substance array
  • Jewelry, luxury watches and various exterior components

Case study

By bonding stainless steel and sapphire at room temperature, we developed a high pressure cell that makes it possible to observe the flow of pressurized liquid and gas.

< Issue >
  • We need large-scale dedicated equipment to secure sapphire using sealing rings, etc.
  • Because the observation part and piping shape differ greatly, the flow changes. It is impossible to observe the state of the fluid in the original piping.
< Solution >
  • We have developed a high pressure cell that makes it possible to observe the flow of pressurized liquid/gas using special technology co-developed with a pressure vessel maker.
    This compact piping observation part has no flow passage change and does not use sealing rings. It can be installed into existing piping with a joint coupler.
  • By using sapphire, which has excellent chemical resistance, for the observation window, it can be used for observing a number of liquids / gases.
  • Bonds a stainless steel fitting and a sapphire observation window
  • Maximum operating pressure: 20 MPa
  • Maximum operating temperature: 100 °C
  • External dimensions: OD Φ20 mm × length 120 mm
  • Sapphire tube dimensions: outer diameter Φ 20 mm x inner diameter Φ 4 mm
  • Observation window dimension: 20 mm in length
  • Material: sapphire, SUS 316

* Maximum length: Up to 50 mm
* Please consult us about the inner diameter of sapphire pipe.

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