Preparation and Formation Mechanism of the Zirconia Coating on Al-Si Alloys by Plasma Electrolytic Oxidation

Wang Ping; Liu Daoxin

doi:10.15980/j.tzzz.2012.12.016

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Preparation and Formation Mechanism of the Zirconia Coating on Al-Si Alloys by Plasma Electrolytic Oxidation
Vol. 32, Issue 12, Pages: 1091-1094(2012)
Published： 2012 ，
DOI： 10.15980/j.tzzz.2012.12.016

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[1]王萍,刘道新.Al-Si合金表面制备ZrO_2等离子体电解氧化涂层的生长机制[J].特种铸造及有色合金,2012,32(12):1091-1094.

Wang Ping, Liu Daoxin. Preparation and Formation Mechanism of the Zirconia Coating on Al-Si Alloys by Plasma Electrolytic Oxidation. [J]. Special Casting & Nonferrous Alloys 32(12):1091-1094(2012)
[1]王萍,刘道新.Al-Si合金表面制备ZrO_2等离子体电解氧化涂层的生长机制[J].特种铸造及有色合金,2012,32(12):1091-1094. DOI： 10.15980/j.tzzz.2012.12.016.

Wang Ping, Liu Daoxin. Preparation and Formation Mechanism of the Zirconia Coating on Al-Si Alloys by Plasma Electrolytic Oxidation. [J]. Special Casting & Nonferrous Alloys 32(12):1091-1094(2012) DOI： 10.15980/j.tzzz.2012.12.016.

摘要

采用等离子体电解氧化方法在Al-Si合金表面制备了氧化锆涂层。通过SEM、XRD研究了涂层的显微组织和相组成。结果表明

在氧化初期

涂层生长为典型的电化学极化控制的阳极沉积阶段

生长速率较快

且主要以向外生长为主;随处理时间的延长及涂层增厚

涂层生长速率有所降低

且主要以向内生长为主。涂层主要由t-ZrO2、m-ZrO2、α-Al2O3和γ-Al2O3组成

t-ZrO2为涂层的主晶相。随着氧化反应的进行

涂层表面由等离子体放电形成的微孔逐渐过渡为重复堆积的陶瓷颗粒

颗粒尺寸为1～2μm。

Abstract

Zirconia coating was prepared on Al-Si alloys by plasma electrolytic oxidation（PEO）in the alkaline electrolyte containing Zr（OH）4 powders.The composition and structure of the coating were investigated by SEM（scanning electron microscope）and XRD（X-ray diffraction）.The results show that in the initial stages of oxidation

the growth of coating belongs to the stage of anodic oxidation controlled by electrochemical polarization.The growth of coating is characterized by outward growth with a faster growth rate.With increasing in time and thickness of the coating

the growth of coating is characterized by in-growth with the decrease of growth rate.The coating consists of t-ZrO2

m-ZrO2

α-Al2O3 and γ-Al2O3

in which t-ZrO2 is dominant in phase with distributed in outer layer of the coating

while α-Al2O3 appears in inner layer of the coating.The coating surface exhibits particle structure with size of 1～2μm.In the process of plasma electrolytic oxidation

Zr（OH）4powders move and deposit on the mouth of plasma discharge channel under electric field force to transform into ZrO2 as a result of the high temperature of plasma discharge.