Tube Inner Coating of Non-Conductive Films by Pulsed Reactive Coaxial Magnetron Plasma with Outer Anode

Musab Gasab,Takemi Sato,Hiroyuki Sugawara,Hiroshi Fujiyama

doi:10.3390/coatings8030115

Abstract

The double-ended coaxial magnetron pulsed plasma (DCMPP) method with auxiliary outer anode was introduced in order to achieve the uniform coating of non-conductive thin films on the inner walls of insulator tubes. In this study, titanium (Ti) was employed as a cathode (sputtering target), and a glass tube was used as a substrate. In an argon (Ar) and oxygen (O2) gas mixture, magnetron plasma was generated. Oxygen gas was introduced to deposit a titanium oxide (TiO2) film. A comparison between films coated with and without an auxiliary outer anode was made. As a result, it was clearly shown that the DCMPP method using an auxiliary outer anode enhanced the uniformity of the deposited non-conductive film compared to the conventional DCMPP method. Moreover, the optimum conditions under which the thin TiO2 film was deposited on the inner wall of the glass tube were revealed. From the results, it was supposed that the auxiliary outer anode contributed to the uniformity of the distributions of deposited negative charge on the non-conductive film and consequently the electric field and the plasma density uniform.

Highlights

Narrow tubes are widely used in the industry for many applications such as the delivery of gas, water, cooling substances, etc. [1]
It was supposed that the auxiliary outer anode contributed to the uniformity of the distributions of deposited negative charge on the non-conductive film and the electric field and the plasma density uniform
The extended anode effect cannot be used for insulator tube coatings of non-conductive or high resistivity films, because electrons charge up the tube inner walls and prevent plasma from spreading along the tube, as reported in our previous article [12]

Summary

Introduction

Narrow tubes are widely used in the industry for many applications such as the delivery of gas, water, cooling substances, etc. [1]. It is indispensable to improve the attributes of the inner walls of such tubes. In this respect, several investigations have been performed [2,3,4,5,6,7,8,9,10]. The extended anode effect cannot be used for insulator tube coatings of non-conductive or high resistivity films, because electrons charge up the tube inner walls and prevent plasma from spreading along the tube, as reported in our previous article [12]. New methods for the uniform coating of non-conductive or high resistivity films on the inner walls of insulator tubes are required

Methods

Results

Discussion

Conclusion