Effects of Carbonization of Filaments on CVD Diamond Thick Films Prepared by HFCVD Method
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UCTION, STRUCTURE, PROPERTIES
Effects of Carbonization of Filaments on CVD Diamond Thick Films Prepared by HFCVD Method Fuming Denga, *, Cen Haoa, Zhenhai Guoa, Shuang Wanga, Xiang Boa, and Zhiyan Zhaoa a
Institute of Super-Hard Cutting Tool Materials, China University of Mining and Technology (Beijing), Beijing, 100083 China *e-mail: [email protected] Received March 12, 2019; revised March 12, 2019; accepted January 8, 2020
Abstract—Hot filament CVD method has many advantages such as simple equipment, easy operation and low expenses, which make it the most widely used method in industrial producing diamond thick film. In this paper, tantalum filament is used in the hot filament chemical vapor deposition apparatus to carbonize under different temperature for different time, then nucleation experiments are carried out on molybdenum substrate. SEM and EDS are used to observe the surface morphology and analyze the components of the carbonized filament and substrate. The results show that lasting the carbonization time can improve the nucleation density in preparing diamond thick film,the adhesion of the diamond film also increases. Electrical resistance of the filament after carbonization can be used as a criterion to determine whether it is fully carbonized or not. Keywords: hot filament chemical vapor deposition, diamond thick film, filament carbonization, SEM, nucleation density DOI: 10.3103/S1063457620050160
1. INTRODUCTION Diamond has a very high hardness and wear resistance, its excellent mechanical properties make it has a wide range of applications in the field of mechanical processing [1]. Practical application of CVD diamond film is divided into two kinds, film and thick film. CVD diamond film is usually deposited directly on the surface of the cemented carbide substrate, how to improve the adhesion between the film and the substrate is still a subject for further study [2–6]. The self-supporting diamond thick film can be soldered to the desired substrate by brazing technology, which overcomes the shortcomings that the bonding strength between CVD diamond film and substrate is hard to meet the requirements, thus the application range of CVD diamond thick film in mechanical processing is expanded [7–10]. Preparation of diamond thick film by hot-filament CVD method is simple and inexpensive, and it can be used to prepare diamond thick film in large quantities, which is the main method used in industrialization [11–14]. The general thickness of thick diamond films which produced by hot filament CVD can reach hundreds of micrometers or even centimeters, so the deposition time takes longer, but the factor determining the deposition time is the life of the filament, so how to extend the life of the filament has become one of the key technologies of diamond thick film’s preparation [15–19]. The carbonization of the filament not only affects the life of the filament, but also increases the nucleation density of the diamond and reduces the contamination of the filament material with the sample, which is the most cri
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