![]() Fly and bottom ash samples were collected to determine its composition via scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). In this study, the flame emission spectra are measured from the combustion of biomass in a boiler, from which the ratios of alkali metals (sodium and potassium) are determined. To mitigate particulate emissions, an understanding of the formation pathways of the gaseous species from combustion of biomass is required. If the temperature is high enough, these ash deposits form slags, decreasing the heat transfer efficiency. adhesives that allow ash to deposit on heat transfer surfaces (normally for producing steam). The particulate emissions are initially formed through the nucleation of gaseous species, such as volatile organic compounds (VOC), semi-volatile organic compounds (SVOCs) and alkali metals. ▶ After ns pulses the surface was relatively smooth and only slightly re-molten.īiomass is increasingly used for providing heat and power via combustion, and its associated particulate emissions have been known to cause environmental, operational and health issues. ▶ The laser-deposit interaction resulted in melting and evaporation of the surface layer. ▶ The cleaning with ns and μs pulses resulted in the external deposit layer removal. ▶ The main components of the corrosion layers are C, O, Cu and P. The investigations included observations in SE and BSE modes and point analyses of the chemical composition by EDS.Research highlights▶ The materials of the investigated archaeological objects (bow and ring) is bronze. The samples were examined using scanning electron microscopes equipped with EDS. The surface topography as well as the chemical composition of the deposits and cleaned surfaces were investigated. ![]() The phase composition of the corrosion layers was determined by using Raman spectroscopy. The materials of which these artefacts were made of, as well as corrosion products on these objects, were studied by using a variety of analytical techniques. The bow and bronze ring had ornamental longitudinal grooving and were part of burial jewellery. Both objects came from a cemetery which is located in the garden complex of Wilanow Palace in Warsaw and are dated from XII to XIII century. Two archaeological objects made of copper alloys were studied: a bow and a ring. ![]() The paper presents the results of laser cleaning of the archaeological metal objects using two time widths of pulsed laser radiation, which are around 150 μs and around 120 ns. ![]() Laser cleaning of the cuprite corrosion layer was shown to be not self-limiting but was found to provide a more sensitive method of removing unwanted paint than JOS cleaning. An initial study was also carried out to compare laser, abrasive (JOS) and steam (DOFF) cleaning techniques on various copper surfaces. The discoloration effect induced by laser radiation on these surfaces was then investigated using a range of analytical techniques: Optical Microscopy, Visible Spectrophotometry, Optical Metallography, X-Ray Diffraction, Scanning Electron Spectroscopy, Energy Dispersive X-Ray Spectroscopy and X-Ray Photoelectron Spectroscopy. ![]() Non-corroded, naturally and artificially oxidised copper, brass and bronze samples, as well as natural brochantite layers on copper, were irradiated with Nd:YAG laser radiation (λ = 1064 nm, pulse duration 10 ns) at various fluence levels. AUTHORS PERSONAL COPY - Laser interactions with copper and copper alloys used in outdoor sculpture in the UK were studied in order to characterise a discoloration phenomenon appearing after laser cleaning of cuprite layers: turning from the typical red-brown colour of cuprite to a grey-purple tinge. ![]()
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