| Budget Amount *help |
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1994: ¥6,500,000 (Direct Cost: ¥6,500,000)
|
|---|
| Research Abstract |
In this study, the liquid Mn and Mn-Cu alloys penetration treatment for YSZ (8wt%Y_2O_3) coating plasmasprayd on SS400 steel substrate was carried out by heating in a vacuum, Ar or N_2 atmospheres respectively, to improve the mechanical properties of porous YSZ coating. The main results include the following.
1. The penetration of liquid Mn-Cu alloys in connected porosity of YSZ coatings was observed for alloys over 35 wt%Mn content by heating in a vacuum of *1.33*10^<-1> Pa and in Ar or N_2 gas atomospheres at 1 atm. The penetration characteristics of the liquid Mn-Cu alloys in connected porosity were clarified by the experiment and calculation analysis.
2. Non connected porosity and densification of the YSZ coating occurred when ZrO_2 particles were sintered with liquid Mn-Cu alloys that penetrated the porous coating. The volume quantity of ZrO_2 phase reached over 99% for the coatings heat treated with Mn-20wt%Cu alloy at 1473K for 7.2ks. It was recognized that the microstructure and
… More
densification rate can be controlled by change of Mn-Cu alloys composition and heat treatment condition.
3. Transformation from monoclinic to cubic structure was found for monoclinic ZrO_2 coating heat-treated with Mn or Mn-Cu alloys, with diffusion of Mn into the coating particles, and this effect can also keep stable the structure for the YSZ coating with same treatment in high temperature.
4. Increasing of bonding strenghness between YSZ coating and steel substrate was recognized by forming of the reaction layr on the interface with densitification and strengthening of the coating after heat treatment with Mn-Cu alloys.
5. The fracture toughness, Young's modulus, Vickers hardness, fracture stress and electric conductivity of YSZ coating after heat treatment with Mn and Mn-Cu alloys were improved greatly by liquid phase sintering, compared with the as-sprayd YSZ coating. For instance, the fracture toughness and Vickers hardness of YSZ coating heat treated with Mn-20wt%Cu alloys were about 4.7 MN/m^<3/2> and 1300Hv, respectively, and these values reached the same levels as those of sintered yttria-stabilized PSZ. Less
|
