Here, we report for first time the successful preparation of a Gold (III) Nitrate (Au(NO3)3) water-based precursor for use in the bottom up process Ultrasonic Spray Pyrolysis (USP). Due to its limited solubility in water, the precursor was prepared under re-flux conditions, having Nitric acid (HNO3) as the solvent and Ammonium Hydroxide (NH4OH) as the neutralizer. This precursor enabled through USP synthesis of Gold nanoparticles (AuNPs) and in-situ formation of NO2- and NO3- ions with low concentration, which were caught directly in de-ionized water in a collection system. These ions were proved to act as AuNPs` stabilizers. Investigations showed that AuNPs were mono-dispersed and spherically shaped with size distribution in three groups: the first contains 5.3% of AuNPs with 2r ( 15 nm, the second contains 82.5% of AuNPs with 2r between 15 nm - 200 nm, and the third contains 12.2% of AuNPs with 2r ) 200 nm. UV-vis spectroscopy revealed AuNPs` maximum absorbance peak of 528 nm. Additionally, Scanning-TEM (STEM) observations of the smallest AuNPs (2r ( 5 nm) revealed atomically resolved coalescence phenomena induced by the electron beam interaction. Four stages of the particle growth process were distinguished as (i) AuNPs` movement and rotation, (ii) Necking mechanism (iii) Orientation attachment at matching facets, and subsequent (iv) Reshaping of AuNPs via surface diffusion. This provides an important insight into the AuNPs` formation/synthesis process.
COBISS.SI-ID: 21568022
The present invention the Manufacturing of High Strength and Heat Resistant Aluminium Alloys Strengthened by Dual Precipitates relates to a high-strength and heat-resistant aluminium alloy and a method for producing the same. The patent describes the chemical compositions of the alloys and the manufacturing route of their production.
COBISS.SI-ID: 21649686
Samples of Nitinol were oxidized using different procedures in order to improve their biocompatibility and prevent the release of Ni. The evolution of the surface oxide films was monitored using Auger electron spectroscopy (AES). The only procedure that led to the formation of nickel-free oxide films involved a pre-treatment with hydrogen plasma for 10 s followed by a treatment with a plasma composed of 90% H2 and 10% O2. Optical emission spectroscopy revealed an extremely high dissociation fraction for both the hydrogen and oxygen molecules at a discharge power of 600 W, where the luminous plasma was concentrated in a volume of about 0.1 dm3. The extreme chemical reactivity of such a plasma resulted in the formation of an oxide film in about 15 s, meaning that external oxidation took place. The biocompatibility investigations, performed according to the ISO standard protocol using L929 cells, showed the absence of any cytotoxic effects that might be due to a contact between the biological materials and nickel. The investigation of nickel release of samples exposed to Hank's solution, measured by ICP-OES showed negligible Ni concentrations.
COBISS.SI-ID: 21981974
Within the current literature there exists a vast amount of data, derived from numerous observations confirming a sluggish bainite formation at low temperatures. This feature is so predominant it is considered an inherent property of the bainite transformation, and has been known as far back as the very first mention of bainite, where the steel was transformed at 200°C in excess of 10 days. The new methodology and alloy design concept of KAB (Kinetically activated bainite) steels enables the formation of carbide free nanostructured bainite in a matter of seconds. The bainite formed within the new grade is very fine and exhibits a hardness of up to 66HRc upon oil quenching, which enables the obtainment of tensile strengths as high as 2800 MPa, variants containing large amount of retained austenite achieve predominantly uniform elongations due a pronounced TRIP effect. This contribution focuses on the microstructural characterization of these steels, using light microscopy, field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) the formation of the micro structure and the mechanical properties obtained during continuous cooling.
COBISS.SI-ID: 21792790
This article studies the synthesis of bimetallic Fe/Au submicron particles with Ultrasonic Spray Pyrolysis (USP). The combination of Fe particles` ferromagnetism with Au nanoparticles` (AuNPs) surface plasmon resonance has gained a high interest in biomedical and various other applications. Initial investigations for producing Fe/Au particles with USP were carried out in order to study the particle formation mechanisms. Firstly, three precursor salt solutions (Fe acetate, Fe nitrate and Fe chloride) were used to produce Fe oxide particles and study their effect on particle morphology through characterisation by Scanning and Transmission Electron Microscopy (SEM and TEM) with Energy Dispersive X-ray spectroscopy (EDX). These precursor salts produce three types of submicron particles, a mesh of primary nanoparticles, spherical particles and irregular particles, respectively. Next, different solution combinations of precursor salts of Fe and Au were used with the USP. The obtained particles were characterized, and similarities were then examined in the particle formation of pure Fe oxide and Fe/Au particles. The effects of using different salts were analysed for formation of favourable morphologies of Fe/Au particles. The combinations of Fe chloride/Au chloride and Fe chloride/Au nitrate in the precursor solution indicate potential in synthesising bimetallic Fe/Au submicron particles with the USP process.
COBISS.SI-ID: 21363478