Synthesis of Multicomponent Coatings by Electrospark Alloying with Powder Materials

Abstract

The results of systematic studies of the electrospark alloying process with the introduction of dispersed materials into plasma of low-voltage pulsed discharges are presented. Technological methods have been developed for supplying the powder material straight into the treatment zone through a hollow electrode of an anode or from the side, with the electrode-anode periodically contacting the substrate of cathode. It has been established that under the same energy regimes, when powder materials were introduced into the discharge zone, the increase in the mass of the cathode per time unit increases from 10 to 15 times or more. This study presents the process of synthesis of carbide phases (TiC and WC) during electrospark alloying of steel substrates with electrodes made of Ti, W, and graphite, with additional supply powders of these materials into the processing zone. A process has been developed for the synthesis of ternary compounds, so-called MAX-phases: Ti2AlC, Ti2AlN and Ti3SiC2 by electrospark alloying with powder compositions TiAlC, TiAlN and TiSiC. These MAX phases exhibit a unique combination of properties that are characteristic of both metals and ceramics. Energy modes of the processing were optimized, which resulted in high-quality coatings with the maximum content of carbide phases and ternary compounds. It has been established that the energy of electrical pulses during electrospark alloying, when powders of materials are fed into the interelectrode gap, ranges from 0.8 to 3.0 J, depending on their thermal physical properties. High wear and corrosion resistant characteristics of C45 structural steel with such electrospark coatings are obtained. The wear of steel with coatings in comparison with uncoated steel decreased by an average of 5.5–6.0 times. It was estimated the high corrosion resistance of 40X13 steel coated with TiC and WC in 3% NaCl solution. The corrosion current for these coatings is 0.044 and 0.075 A/cm2, respectively, and is significantly less than for coatings made of TiAlC, TiAlN, and TiSiC compositions. X-ray phase and optical metallographic microscopy analyses enabled the display of the amorphous-crystalline nature of the coatings.

Improving the Surface Quality and Tribological Characteristics of 3D-Printed Titanium Parts through Reactive Electro-Spark Deposition

“…Low-melting Al-Si alloys with composition and designations AlSi9 and AlSi12 [20,[23][24][25] were selected for RESD. The electrodes with a homogenised chemical composition and fine metal-glass structure were created using a special technology developed at the National University of Science and Technology, MISIS-Moscow [20,23].…”

“…The results obtained in these studies create prerequisites for the targeted synthesis of increased amounts of certain phases in the surface layer by varying the modes and processing electrodes. For example, in RESD, with AlSi electrodes and the use a nitrogen environment and an appropriate selection of the duration and energy of the pulses (E = 0.04-0.07 J), TiN and TiCN can be synthesised in the formed layer, as can AlN or TiAlN, and various others can be purposefully synthesised in the formed layer [18,23,25,26,28]. In an air or oxygen environment, titanium oxides, Al 2 O 3 and solid solutions of oxygen and nitrogen in titanium can be produced in the layer, and it is widely known that the oxide-nitride particles trapped in the titanium-aluminium matrix give higher hardness and wear resistance.…”

“…Signs of active interaction of the electrode and substrate material under conditions of local melting in the ESD process, in which the properties of the substrate are improved as a result of the synthesis of new phases, have been noted in many works [23][24][25][26][27]. In addition, the extremely high cooling rate of the reactive melt (10 5 -10 6 • C/s) [19,21,22] allows the formation of new ultra-dispersed, amorphous and nanoscale structures with improved wear resistance.…”

Surface Characteristics, Properties and Wear Resistance OF TIB2 BASED Hard-Alloy Coatings Obtained by Electrospark Deposition at Negative Polarity on Ti6Al4V Alloy

“…Electrodes: Electrodes of TiB2-TiAl, (74%Ti + 12%B + 14%Al) dispersive reinforced with 7% nano-sized ZrO2 and NbC particle additives were used to form coatings with amorphous and nanostructured phases and to increase the microhardness and wear resistance of coated surfaces [18][19][20][21][25][26][27][28][29][30].…”

Investigation of the Lubricated Tribo-System of Modified Electrospark Coatings

“…Recently, TiAlC-based coatings have attracted considerable attention, as they may exhibit good bearing capacity in the marine environment and ground industry in terms of good anticorrosion properties and wear resistance [9,10]. Those coatings are commonly produced by using physical vapor deposition and chemical vapor deposition.…”