Contents lists available at ScienceDirect Wear journal homepage: www.elsevier.com/locate/wear Investigation of erosion temperature in micro-blasting Ruslan Melentiev a , Fengzhou Fang a,b, ⁎ a Centre of Micro/Nano Manufacturing Technology (MNMT-Dublin), University College Dublin, Dublin, Ireland b State Key Laboratory of Precision Measuring Technology and Instruments, Centre of Micro/Nano Manufacturing Technology (MNMT), Tianjin University, Tianjin, China ARTICLE INFO Keywords: Solid particle erosion Impact temperature Micro-blasting Abrasive jet machining ABSTRACT Micro-blasting is a non-conventional subtractive micro-manufacturing technology based on erosion localisation and intensifcation. The thermal aspects of erosion are rarely discussed in the literature and commonly neglected in the analysis of erosion mechanism and quality control of machined surface. This study uses analytical, nu- merical and experimental approaches to explore erosion temperature in relation to micro-blasting of carbon steels. The research shows that, in terms of temperature, airborne erosion by solid particles is a double-natured process; the surface temperature may increase up to a few thousand degrees Celsius after a single impact, yet it dissipates at the subsurface over several microseconds. Melted and adhered drops of the metallic substrate were found in optical images of abrasive particles and SEM images of a machined surface. EDX elemental analysis confrmed that a thin metal layer was deposited on the particle's interface. Despite this, several FEM models and measurements taken by a thermocouple and IR camera—showed that the steady-state temperature is negligible. The heat generated during each impact has sufcient time to dissipate, leaving a residual temperature of a few degrees before the next impact at the same site. This heat accumulation could elevate the temperature to a few hundred degrees, particularly when the workpiece is small, although convective cooling by air fow efectively dominates this efect. In general, small and slow abrasives are recommended to reduce the temperature. Application of alumina particles smaller than 27 µm to blast low-carbon steels produces minimal negative consequences. 1. Introduction Micro-blasting is a non-conventional subtractive micro-manu- facturing technology that recently branched of from abrasive jet ma- chining (AJM). AJM is based on erosion localisation and intensifcation. In micro-blasting, a compressed fow of dry air accelerates abrasive micro-particles to impact the target material, diminishing the volume of the workpiece until it reaches the required geometry. Material is re- moved by means of cutting or ploughing in a ductile substrate or fracturing in a brittle substrate through plastic deformation or crack propagation, respectively. Micro-blasting is applied in the manu- facturing of semiconductors, electronic devices, LCDs, micro mould dies, frictional surfaces with specifc patterns for machinery and bioimplants, etc. Among the various advantages of AJM, including its negligible thermal efect, small cutting force, high machining versatility and high fexibility, cost efciency, energy- and resource-efciency, insensitivity of the machining accuracy to vibrations or temperature changes, slow tool wear, improvement of metallic surface properties via, for example, work hardening and lack of a machining signature and other aspects, recently reviewed in [1], the thermal efect is the least studied and subjected to contradictions. Similar to other tribological processes, solid particle erosion is a combined process; the mechanical load is related to the secondary thermal, chemical and physical reactions between the counterparts [2]. Physical reactions were extensively studied by Finnie, Cofn, Manson, Bitter, Neilson and Gilchrist, Evans, Hutchings and Levy and other scholars since the late 20th century. Their understanding of erosion serves as a foundation for contemporary methods of erosion process control. The chemical reactions that occur during solid particle erosion are described by chemisorption theory. They are mainly based on the surface hydroxylation efect, which was used to develop an elastic re- moval mode for fuid jet polishing of surfaces to Angstrom-scale roughness (e.g.Ra = 1.8 Å), as described by Peng et al. [3]. In contrast to the other two reactions, there have been almost no studies on the thermal aspect of erosion, that gains no controlled advantages to ero- sion-based machining technologies. The thermal conductivity and temperature resistance of the target can be important parameters for the erosion process. Localised deformation induced by the impact of particles and the adiabatic conditions prevailing at high strain rates may produce high temperatures. Since high temperatures afect the https://doi.org/10.1016/j.wear.2018.12.073 Received 4 September 2018; Received in revised form 19 November 2018; Accepted 21 December 2018 ⁎ Corresponding author at: Centre of Micro/Nano Manufacturing Technology (MNMT-Dublin), University College Dublin, Dublin, Ireland. E-mail address: fengzhou.fang@ucd.ie (F. Fang). Wear 420–421 (2019) 123–132 Available online 24 December 2018 0043-1648/ © 2018 Elsevier B.V. All rights reserved. T