Fabrication and examination of oxidation resistance of zinc coated copper and brass components by chemical deposition

Abstract

Abstract:In this work, the structure and the oxidation resistance of Zn deposited Cu and brass metallic components are examined. The deposition was accomplished with pack cementation chemical deposition. The examination of the samples was performed with electron microscopy and X-ray diffraction analysis. It was found that coatings on Cu substrate consist of two layers with different Zn concentrations, while coatings on brass were single layered with almost constant Zn concentration. The presence of distinct Zn-Cu phases was revealed in both cases. The subjection of the as coated samples together with the uncoated substrates in air at 400ºC showed that both Zn coated samples have enhanced resistivity in such atmospheres, as most of the coating remained mostly unoxidised, and the substrates were fully protected. On the contrary, the bare substrates appear to have undergone severe damage as brittle oxides were formed on their surface.

Wear Resistance Improvement of Copper Alloys Using a Thermochemically Obtained Zinc-Rich Coating

“…The results report the presence of a Cu5Zn8 -like structure, phase (JCPDS 65-6566, crystal system cubic, space group I43m, cell parameter 8.85-8.89 Å). These results agree with literature [22][23][24][25][26][27][28][29][30][31], and show the presence of the γ phase of the Zn-Cu system, which is a harder phase.…”

“…In the case of bronze, the X-Ray analysis show the formation of a cubic structure of Copper Zinc (Cu64Zn36, JCPDS card No 50-1333) with Miller's index equal to a=b=c=3.69612 Å and a phase Cu5Zn8 (JCPDS 65-6566, crystal system cubic, space group I43m, cell parameter 8.85-8.89 Å). It is confirmed for brass case and according to various references [22][23][24][25][26][27][28][29][30][31], the presence of γ phase of the Cu-Zn system. Also, a cubic structure of Copper Oxide in which a=b=c= 4.26960 Å is perceived.…”

“…This loss of symmetry, coupled with the fact that in γ brass, is obtained the maximum amount of distortion, will probably account for the exceptional hardness of γ brass as compared with the hardness of the other alloys in the series. As discussed in [22][23][24][25][26][27][28][29][30][31], the complex crystalline structure of this phase is associated with a high defect density that would also contribute to greater coating hardness. Both coated materials show a linear relationship between their microhardness and the distance from the surface, in the case of bronze there is a correlation index of 0.41, for brass a value of 0.69 is obtained.…”

Resistance of different Zn coatings at elevated temperature air environments

“…A promising technique that could be used alternatively is chemical vapour deposition by pack cementation. [2][3][4][5][6][7][8] With this method, the formation of zinc diffusion coatings is accomplished by heating the substrate up to 400uC together with a mixture of powders containing zinc and a halide activator. Another commonly used method is combustion thermal spray.…”

Effect of La on intermetallic layer of galvalume

“…The hot dip coating can effectively protect the iron and steel products as a barrier and prolong the products' working life. [1][2][3][4] In recent years, a series of coatings has been studied, which were basically made up of zinc alloys: Al-Zn alloys, Zn-Ti alloys, Zn-Mn alloys, Zn-Co alloys and Al-Zn-Mg-RE alloys. [5][6][7][8] Among those alloys, the galvalume (55%Al-Zn-1?6 wt-%Si) coated steel has a better anticorrosive performance than zinc coating and has a high temperature oxidation resistant property like that of aluminium coating.…”