A new method for fabrication of nanohydroxyapatite and TCP from the sea snail Cerithium vulgatum

Biphasic bioceramic nanopowders of hydroxyapatite (HA) and β-tricalcium phosphate (TCP) were prepared from shells of the sea snail Cerithium vulgatum (Bruguière, 1792) using a novel chemical method. Calcination of the powders produced was carried out at varying temperatures, specifically at 400°C and 800°C, in air for 4 hours. When compared to the conventional hydrothermal transformation method, this chemical method is very simple, economic, due to the fact that it needs inexpensive and safe equipment, because the transformation of the aragonite and calcite of the shells into the calcium phosphate phases takes place at 80°C under the atmospheric pressure. The powders produced were determined using infrared spectroscopy (FT-IR), X-ray diffraction, and scanning electron microscopy (SEM). The features of the powders produced along with the fact of their biological origin qualify these powders for further consideration and experimentation to fabricate nanoceramic biomaterials. © 2014 O. Gunduz et al

Wettability characteristics of carbon steel modified with CO2, Nd:YAG, Excimer and high power diode lasers

Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of a common mild steel (EN8) was found to effect changes in the wettability characteristics of the steel, namely changes in the measured contact angle. These modifications are related to changes in the surface roughness, changes in the surface oxygen content and changes in the surface energy of the mild steel. The wettability characteristics of the selected mild steel could be controlled and/or modified by laser surface treatment. A correlation between the change of the wetting properties of the mild steel and the laser wavelength was found

Carbon steel wettability characteristics enhancement for improved enamelling using a 1.2 kW high power diode laser

High-power diode laser (HPDL) surface treatment of a common engineering carbon steel(EN8) was found to effect significant changes to the wettability characteristics of the metal. These modifications have been investigated in terms of the changes in the surface roughness of the steel, the presence of any surface melting, the polar component of the steel surface energy and the relative surface oxygen content of the steel. The morphological and wetting characteristics of the mild steel and the enamel were determined using optical microscopy, scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), energy-dispersive X-ray (EDX) analysis and wetting experiments by the sessile drop technique. This work has shown that HPDL radiation can be used to alter the wetting characteristics of carbon steel so as to facilitate improved enamelling

High power diode laser modification of the wettability characteristics of an Al2O3/SiO2 based oxide compound for improved enamelling

High power diode laser (HPDL) surface melting of a thin layer of an amalgamated Al2O3/SiO2 oxide compound (AOC) resulted in significant changes in the wettability characteristics of the material. This behaviour was identified as being primarily due to: (i) the polar component of the AOC surface energy increasing after laser melting from 2.0 to 16.2 mJm-2, (ii) the surface roughness of the AOC decreasing from an Ra value of 25.9 to 6.3 μm after laser melting and (iii) the relative surface oxygen content of the AOC increasing by 36% after laser melting. HPDL melting was consequently identified as affecting a decrease in the enamel contact angle from 1180 prior to laser melting to 330 after laser melting; thus allowing the vitreous enamel to wet the AOC surface. The effective melt depth for such modifications was measured as being from 50 to 125 μm. The morphological, microstructural and wetting characteristics of the AOC were determined using optical microscopy, scanning electron microscopy, energy disperse X-ray analysis, X-ray diffraction techniques and wetting experiments by the sessile drop technique. The work has shown that laser radiation can be used to alter the wetting characteristics of the AOC only when surface melting occurs

The influence of a high power diode laser (HPDL) generated glaze on the wetting characteristics and the subsequent HPDL enamelling of ordinary Portland cement

High power diode laser (HPDL) surface glazing of the ordinary Portland cement (OPC) surface of concrete was found to effect significant changes in the wettability characteristics of the OPC. This behaviour was identified as being primarily due to: (i) the polar component of the OPC surface energy increasing after HPDL glazing from 3.46 to 15.56 mJm-2, (ii) the surface roughness of the OPC decreasing from an Ra value of 21.91 to 2.88 m after HPDL glazing and (iii) the relative surface O2 content of the OPC increasing by 4.5at% after HPDL glazing. HPDL glazing was consequently identified as occasioning a decrease in the enamel contact angle from an initial value of 1090 to 310, thus allowing the vitreous enamel to wet the OPC surface

Identification of the principal elements governing the wettability characteristics of ordinary Portland cement following high power diode laser surface treatment

The elements governing modifications to the wettability characteristics of ordinary Portland cement (OPC) following high power diode laser (HPDL) surface treatment have been identified. Changes in the contact angle, , and hence the wettability characteristics of the OPC after HPDL treatment were attributed to: reductions in the surface roughness of the OPC; the increase in the surface O2 content of the ceramic and the increase in the polar component of the surface energy, . What is more, the degree of influence exerted by each element has been qualitatively ascertained and was found to differ markedly. Surface energy, by way of microstructural changes, was found to be by far the most predominant element governing the wetting characteristics of the OPC. To a much lesser extent, surface O2 content, by way of process gas, was also seen to influence to a changes in the wettability characteristics of the OPC, whilst surface roughness was found to play a minor role in inducing changes in the wettability characteristics

Wettability characteristics of an Al2O3/SiO2-based ceramic modified with CO2, Nd:YAG, excimer and high-power diode lasers

Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of an Al2O3/SiO2 based ceramic was found to effect significant changes in the wettability characteristics of the material. It was observed that interaction with CO2, Nd:YAG and HPDL radiation reduced the enamel contact angle from 1180 to 310, 340 and 330 respectively. In contrast, interaction with excimer laser radiation resulted an increase in the contact angle to 1210. Such changes were identified as being due to: (i) the melting and partial vitrification of the Al2O3/SiO2 based ceramic surface as a result of interaction with CO2, Nd:YAG HPDL radiation. (ii) the surface roughness of the Al2O3/SiO2 based ceramic increasing after interaction with excimer laser radiation. (iii) the surface oxygen content of the Al2O3/SiO2 based ceramic increasing after interaction with CO2, Nd:YAG and HPDL radiation. The work has shown that the wettability characteristics of the Al2O3/SiO2 based ceramic could be controlled and/or modified with laser surface treatment. In particular, whether the laser radiation had the propensity to cause surface melting. However, a wavelength dependance of the change of the wetting properties could not be deduced from the findings of this work

Glasses and glass-ceramics in the CaO–MgO–SiO2 system: diopside containing compositions - a brief review

Among different silicate systems, CaO−MgO−SiO2 is the one of the most promising due to abundance of reagents, easier fabrication, improved performance, and wide range of application. Analysis of the current literature sources denotes that phase diagram of CaO−MgO−SiO2 system is regularly used by researchers worldwide as constitutive model for synthesis glass-ceramic materials (GCs) possessing an adequate combination of high chemical durability, mechanical and electrical properties. In recent years, materials from this system attracted extra interest for applications in bone tissue repair owing to their ability to induce hydroxyapatite formation in contact with body fluids and to be resorbed in controllable degradation rate. In this brief review diopside containing compositions are specifically discussed. The main goal is to provide critical analysis of the experimental trials directed on synthesis of GC materials in the CaO−MgO−SiO2 system. Glass compositions were analysed through the standpoint of their location in the relevant region, or phase field, within a phase diagram to guide GC production and to make educated choices of compositions and processing parameters. Apart from Introduction and Conclusions this review comprises five consecutive parts. In the first part, constitution of phase diagram of CaO−MgO−SiO2 system is comprehensively discussed with connection to melts’ crystallization path and crystalline phase formation. In the second part, special attentiveness is drawn towards diopside- containing GCs produced from wastes and non-expensive natural raw materials. In this regard and taking into consideration presence of Al2O3 in the majority types of wastes, cross sections of CaO−MgO−SiO2−Al2O3 system with 10, 15 and 20% of Al2O3 are suggested to utilize when anticipating ultimate crystalline phase(s) formation. The following parts of this review are mostly addressed to recent advancement in producing optimized diopside-containing glass–ceramic biomaterials for bone repair as well as innovative sealants for solid oxide fuel cells (SOFC). Likewise, some other active areas of research and application for diopside containing GC compositions are briefly discussed.publishe

EUROMAT 2019 Symposia on Processing

This issue of JMEP contains invited, peer-reviewed papers presented at the European Congress and Exhibition on Advanced Materials and Processes (EUROMAT 2019), held on September 1–5, 2019, in Stockholm, Sweden, in two symposia from the Area C “Processing”: C6 “Joining,” organized by Anna Zervaki (University of Thessaly, Greece), Ivan Kaban (IFW Dresden, Germany), and C. Sommitsch (Technische Universität Graz, Austria) C8 “Interface Design and Modelling, Wetting, and High-Temperature Capillarity,” organized by Pavel Protsenko (M.V. Lomonosov Moscow State University, Russian Federation), Fabrizio Valenza (CNR—ICMATE, Genoa, Italy), and Simeon Agathopoulos (University of Ioannina, Greece) The research works in the field of joining technologies, presented at the C6 symposium, concerned soldering, brazing, diffusion bonding, resistance spot welding, friction stir welding, and riveting techniques. The symposium C8 covered research topics on grain boundary wetting, surface energy of liquid metals and interfacial phenomena, considering fundamental as well as applied issues related to materials joining, and interface design. We wish to thank the authors for the written contributions and acknowledge the reviewers for their careful reading and evaluation of the manuscripts and valuable suggestions to improve the quality of the papers. We are grateful to the editor-in-chief of JMEP, Dr. Rajiv Asthana, and the ASM journal staff, including Mary Anne Fleming, senior content developer; Kate Doman, content developer (journals); and Vincent Katona, production coordinator; for the opportunity to publish the symposia contributions in this issue and for their professional and friendly support during the entire reviewing and publication process. We hope this collection will stimulate fresh thinking and promote further research on joining and interfacial phenomena

Ultra broadband yellow emitting lead-free metal halide perovskite like compounds with near-unity emission quantum yields

Metal halide perovskites (MHPs) are interesting semiconductor materials with potential for use in optoelectronic and photonic devices. Their practical applications are hindered due to the negative environmental effects of the lead ions (Pb2+) used in these materials and stability issues. Exploring new environmentally friendly materials with lead-free metal halides and investigating the factors affecting their optical properties and stability are essential. The broadband emission and high (near-unity; ∼100%) photoluminescence quantum yield (PLQY) of low-dimensional copper(i) halides make them great candidates for the next-generation luminescent materials for lighting applications. Here, a Cu(i) iodide based organic/inorganic hybrid halide (benzo-15-crown-5)2NaH2OCu4I6 (BCNCI) with a zero-dimensional (0D) cluster was prepared. The BCNCI has a broadband yellow emission peaked at 548 nm with a near-unity PLQY (99.1%) upon excitation at 365 nm (ultraviolet). Upon excitation at 450 nm (blue), a high PLQY of 82% was also achieved. The luminescence mechanism was discussed in detail. Interestingly, BCNCI exhibits ultra-broad band excitation in the 300-500 nm range, which matches commercially available UV and blue-emitting chips. Compared to commercial YAG:Ce3+ phosphors, the emission spectrum is sufficiently broad to cover the visible spectral region. This work illustrates a good example of developing an environmentally friendly white light source, using high-performance copper halides with adequate broadband excitation and emission