SPS has superior features such as short-time sintering, homogeneous sintering, and a wide range of target materials. It means that SPS equipment is required to be able to continuously sinter high-quality samples in a short time with good reproducibility. What kind of performance is specifically required for SPS equipment?
(a) Durability
SPS equipment has to have excellent durability to be capable for rapid temperature change. It employs electrode parts and chamber structure that can be used at sintering temperatures exceeding 2000 degree C. Not only for the strength for the high temperature but the durability for repeated heating and cooling are required.
(b) Pressurization characteristics for sudden temperature changes
The reliable pressurization mechanism is required to provide stable control even when the SPS temperature rises rapidly, the sample expands and contracts during rapid cooling, and the high-temperature sample shrinks during sintering.
(c) Precise measurement and control of sample temperature with large temperature changes
Stable temperature measurement and control performance at rapid heating such as 100°C/min. , 200°C/min (even 500°C/min or more) is required .
(d) Capability to create/control the appropriate sintering atmosphere
SPS often uses a sintering atmosphere of several to several tens of Pa using a rotary pump, but a high vacuum such as 5 x 10-3 Pa or an inert gas atmosphere is also required at some points.
(e) Reproducibility of sintering
SPS equipment is expected to reproduce the characteristics and performance required for the sintered compact.
(f) Reliability and safety
The above (a) – (e) should be well maintained, and the same performance should be exhibited at any time. Moreover, in the case of SPS equipment, higher reliability is required in particular due to the harsh operating conditions such as rapid temperature rise and pressurization at high temperature.
In addition, the equipment must be designed and manufactured in accordance with safety standards with extreme caution to prevent any risks from human body.
The manufacturer shall present the appropriate instructions including maintenance management and determine operating protocols after due consultation.
SPS equipment has been successfully applied to actual product and some of them are used as production system. This fact proves the product quality of sintered compact as a result of reproducibility of rapid temperature rise, pressurization control, etc.
Regarding SUGA’s SPS equipment, it depends on the conditions of maintenance management and usage but many of them are still in a good shape even after 20 years or more in laboratories, factories, etc., and it can be considered as the proof of its high reliability.
For the safety, we conduct risk assessments in accordance with the procedures stipulated in the international standard ISO12100, which is the basic concept of machine safety. We are striving to ensure safety comprehensively, along with instructions for users, including maintenance and safety management.
At the next episode, we would like to introduce the examples of SPS applications.
