Diamond films were synthesized on a Mo substrate using combustion flame. During cooling process, the most diamond films delaminated between the diamond film and the Mo substrate. It was caused by the thermal stresses due to a mismatch of thermal expansion between the diamond film and Mo substrate. In the previous study, a three-step synthesis method was proposed. According to the results, the delamination could be prevented to some extent, but it was not able to protect completely. Scratching treatments on the surface of the substrate and distances from inner cone to the surface of the substrate were remarked as influence factors of the delamination. Experiments were performed with changed parameters of its influence factors, and effects of influence for the delamination were discussed from experimental results. Optimal conditions of diamond film synthesized using combustion flame were discussed in terms of prevention of the delamination.
We propose a quick and controlled cracking method for industrial ceramic waste by applying a steam pressure cracking (SPC) agent. The agent is a non-explosive and low-vibration-type chemical, which was developed by one of the authors of this study. We prepared a concrete specimen that had a diameter and cylinder height of 150 mm. Several grams of the agent cracked the specimen. We could control the cracking better in water than air when the air and water conditions were compared. When tested in water, the agent was placed in the hole of the concrete specimen and ignited, and the specimen could be split into two or three pieces of the same size. However, using another SPC agent that was explosive, the concrete specimen was broken into small fragments and size of the concrete pieces could not be controlled. The crushing mechanism was different for the two cases. The explosive crushed the concrete mainly through elastic shock waves. However, the steam pressure cracking agent breaks the specimen using the steam pressure and shock waves. We demonstrated that the cracking can also be controlled using guide holes. This steam pressure method can be applied to industrial waste as a safe and well-controlled method.
Diamond films were synthesized on a Mo substrate using combustion flame. During cooling process, the most diamond films delaminated from the Mo substrate because of their thermal expansion mismatch. To prevent the delamination, a three-step synthesis method was proposed. The first step was synthesis of the Mo 2 C and the diamond phases on the Mo substrate, and the second and the third steps were synthesis of the diamond phase. The interfacial stress between the film and substrate was calculated by a finite element method. According to the results, the stress in the film made by the method was smaller than that by an one-step synthesis method. The three-step method is useful for synthesizing the diamond film.
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