Study on fabrication of ceramic coatings on Ti–6Al–4V alloy by combined ultrasonic impact treatment and electrospark

Abstract

A method combining ultrasonic impact treatment with electrospark was developed to fabricate ceramic coatings on Ti-6Al-4V alloy. In this paper, the mechanism of the combined process is described in detail. The microstructure, chemical states, phase composition and surface residual stress of the ceramic coated titanium alloy were presented. The coatings mainly consist of carbides of titanium. The hardness of the coating increased significantly owing to the existence of the ceramic phase. Further, the impact process and the narrow space that the shock ball traverses decrease the surface roughness of the sample after the combined process. Finally, the surface residual stress of the sample treated by the combined process is compressive stress.

Corrosion of 2024 alloy after ultrasonic impact cladding with iron

“…The UIT induced hardening of 2024 alloy was explained by the formation of fine grains [16]. In our case, the deformation induced mechano-chemical reactions [15,16] and the formation of the oxide/intermetallic layer [16,20,21] significantly increase the hardness of the surface after the air-UIT process. The XRD analysis confirmed that simultaneous mass-transfer of oxygen and iron in the surface layer facilitates the formation of the complex iron aluminium oxides like spinels FeAl 2 O 4 , AlFeO 3 (Figure 3).…”

Transformations of the Microstructure and Phase Compositions of Titanium Alloys during Ultrasonic Impact Treatment Part III: Combination with Electrospark Alloying Applied to Additively Manufactured Ti-6Al-4V Titanium Alloy

“…One of the promising techniques for improving wear resistance of the Ti-6Al-4V alloy is a method based on a combination of ultrasonic impact treatment with electrospark alloying [18][19][20][21]. As a result of ultrasonic impact electrospark treatment (UIET), continuous hard coatings are formed on the Ti-6Al-4V alloy surface, uniform in thickness and consisting of small drops of the striker (anode) material.…”

Enhanced wear resistance by combined ultrasonic impact and electro-spark melting

“…Previous studies conducted by Liu et al [9][10][11] combined the advantage of UIT and ESD, a new method named ultrasonic impact electro-spark treatment (UIET) was proposed, and its feasibility for the preparation of coatings on Ti-6Al-4V (TC4) was investigated. In the UIET, the target and shock ball are connected to the cathode and anode, respectively.…”

“…The surface roughness and wear properties of specimens under untreated, UIT and UIEMT conditions were investigated in the following. The previous approach [10,11] is referred as ultrasonic impact electro-spark deposition treatment (UIEDT) in order to avoid any confusion.…”