TiAl Surface Coating on Titanium by Plasma Transferred Arc Surfacing and Its Oxidation Behavior

Abstract

In order to improve high-temperature oxidation resistance of titanium, fabrication of TiAl intermetallic compounds as a surface layer by plasma transferred arc surfacing (PTA surfacing) was investigated. Powder of unalloyed aluminum was fed into the plasma during the PTA surfacing and TiAl-based intermetallic layers were successfully synthesized. The surface layers had no cracks and porosities with optimized conditions of the PTA surfacing. The surface layers that largely consist of TiAl and Ti 3 Al phase could be achieved, while the microstructures of them were significantly influenced by the conditions such as the arc current. The TiAl-based layers exhibited high resistance to oxidation under isothermal conditions at 1073 K or less and had practically the same resistance as SUS310S had.

Surfacing – Technologies and Layer Properties (A Review)

“…The heat output of the welding arc is also used for remelting of the pre-deposited layer [14]. The plasma arc can also be used to remelt a deposited layer [21] or apply a layer using the powder injected in the plasma arc [22], [23], [24]. In both cases, the surface of the substrate melts, a welding pool is formed, and during on its crystallization the additive materials participate in the formation of the layer and thus determine its properties.…”

“…In both cases, the surface of the substrate melts, a welding pool is formed, and during on its crystallization the additive materials participate in the formation of the layer and thus determine its properties. When the aim is to obtain intermetallic compounds with the metal of the substrate in the coating, this can be achieved by adding the second metal in the form of a powder [23]. High cooling rates using heat sources with high energy concentration such as electron beam surfacing (EBS) [25], [26], [27], [28] and [29] or laser surfacing (LS) [30] - [39] creates conditions for modifying the surface layer even without the use of filler materials [25] or after a surfacing process has been performed [3], [26].…”

“…The microstructure is examined by optical (OM) [1], [9], [17], [21], [23], [27], [30], [31], [36] ], [42], [43] and electron microscopy (SEM) [1], [10], [11], [14], [21], [22], [23] , [33], [39], [46], [47]. The phase composition is determined by the X-ray diffractometer [18], [23], [27], [31], [33], [36], [39], [45], the transmission diffraction electron microscopy [18] and energy-dispersive X-ray spectroscopy [14], [22], [30], [33], [39]. The X-ray fluorescence method [7] and the atomic emission spectrometer [7] were used to determine the chemical composition.…”

“…In the publications reviewed, the materials used as substrates can be divided into the following main groups: carbon steels [3], [6], [7], [12], [13], [15], [16] 17, 18, 21, 25, 26, 29, 36 and 37; alloyed steels [1], [4], [8], [9], [20], [22], [24], [30], [41] and [42]; highly alloyed steels [5] and [32]; aluminium and aluminium alloys [11], [28], [39], [43], [44] and [45]; titanium and titanium alloys [23], [31], [34] and [35]; ductile cast iron [33] and [40]. The SAS, MIG / MAG, TIG, PST, EBS and LS methods were used to apply the layers to carbon steels.…”

“…In [21] we have shown a hardness of 400 ÷ 1800 HK using NiCrBSiC filler material. In [23] unalloyed aluminium powder is used and a layer is applied to titanium. The particle size is 75 to 147 [nm].…”