Measurement of ZrC properties up to 5000 K by fast electrical pulse heating method
- PDF / 434,541 Bytes
- 8 Pages / 584.957 x 782.986 pts Page_size
- 51 Downloads / 180 Views
Sergey A. Muboyadzhyan Laboratory for technology surface and protective coatings for metallic materials, All-Russian Institute of Aviation Materials, Moscow 105005, Russia (Received 3 October 2016; accepted 2 February 2017)
Sintered zirconium carbide (C/Zr 0.95) was studied by pulsed electrical heating method with microsecond duration. Thermophysical properties such as Joule energy, heat of melting, the specific heat, and electrical resistance were measured in the temperature range of 2500–5000 K by this method for the first time. The steep increase of the specific heat just before melting may be associated with the formation of nonequilibrium pairs point Frenkel defects at high temperatures under fast heating. It was established that the melting of the carbide occurs in the temperature range: solidus—3450 K and liquidus—3850 K, that is close to the values presented in some equilibrium phase diagrams of the system Zr–C. This means that there is no shift of the phase transition points at the heating rates up to 108 K/s, and makes it possible to use this method for the study of high temperature behavior of the complex substances. The comparison of the data of measured properties with the literature data is provided.
I. INTRODUCTION
It is known that the zirconium carbide is widely used in the nuclear industry (protective coating of nuclear fuel),1,2 aviation and aerospace technology (protective coatings of gas turbine system and nozzles of the missiles). Investigation of high temperature properties of carbide and Zr–C phase diagram is important for modern technology and industry. Zr–C phase diagram has been developed for a number of years; one of the variants was proposed in Ref. 3. So far, the phase diagram is being refined, as not all parts of the phase diagram were checked by the experiments. The limitations of stationary research require the development of the pulsed methods of experimental studies of high-temperature properties of zirconium carbide. One of this method, developed in recent years, is the method of millisecond pulsed laser heating, presented in papers.4–6 The advantages of this method are: (i) the possibility of obtaining the highest temperatures; (ii) the absence of the crucible and the absence of the specimen contamination; (iii) the possibility of conducting experiments in a controlled atmosphere at a controlled shape of the laser pulse; (iv) the saving of the specimen after the experiment for further research. However, this method does not allow investigating the bulk properties of the specimen such as enthalpy, heat capacity, electrical
resistance, and the heat of fusion. All of these properties allows you to explore another method of pulsed heating— pulsed electrical heating method.7 This method also makes it possible to measure the true temperature of the specimen in the solid and liquid phase using the black body model.8 Apparently, the method of fast pulsed electric heating was applied for the first time to study carbides in 2011.9 Sputtered film of zirconium carbide with a high carbon cont
Data Loading...
