2001 Fiscal Year Final Research Report Summary
Coloring mechanism and new coloring technic of Cu alloys
| Project/Area Number |
11450270
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Material processing/treatments
|
|---|
| Research Institution | Tokyo National University of Fine Arts and music |
|---|
Principal Investigator |
KITADA Masahiro Tokyo National University of Fine Arts and music, Graduate School Prof., 大学院・美術研究科, 教授 (70293032)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TSURU Touru Tokyo Institute of Tech., Graduate School Prof., 大学院・工学研究科, 教授 (20092562)
SUGIMOTO Katsuhisa Touhoku Univ., Graduate School, Prof., 大学院・工学研究科, 教授 (80005397)
|
|---|
| Project Period (FY) |
1999 – 2001
|
| Keywords | metal craft / coloring / Cu alloy / oxidation / Cu_20 / metal particle / light absorption / corrosion |
|---|
| Research Abstract |
Coloring mechanism, fine structure, and corrosion effect of coloring layers of copper alloys formed in a solution containing copper sulphate and artificial malachite have been investigated. This coloring technic is used in a traditional Japanese metal-craft. Noble coloring technic has also been investigated. The basic structure of coloring layer of Cu alloys is a mixed state of crystalline and amorphous Cu_20. It is thought that the amorphous Cu_20 is formed by diffusion of S and Cl from the solution to the alloy surface. For shakudou, Cu-4%Au alloy, Au very fine crystals distribute in the Cu_20 matrix layer and the average diameter is 5 nm. For brass, Cu-30%Zn alloy, it is observed that Zn species dissolves preferentially in the solution. Therefore, Zn concentration in the oxide layer Cu_20 is very low. For shibuichi, Cu-25% Ag alloy, Cu species is oxidized easily and the crystalline and amorphous Cu_20 are introduced. However, Ag species becomes fine metal particles. A part of residual Ag species distributed in Cu_2O layer makes Ag_2S. The incident light is absorbed mainly by metal fine crystals distributed in the Cu_2O layer and the Cu_2O layer, and the matrix metal reflects the light. Coloring is due to these composite phenomena. The threshold of currnet-voltage characteristic shifts to the direction of the high voltage side by coloring treatment. This means that the corrosion resistance increases by the coloring layer formation. Some basic data to develop new coloring technic are obtained by thermal oxidation and others.
|
