Arc stability characterization of double coated electrodes for hardfacing

The aim of this work is to establish the influence of the relative position of the alloy charge C-Cr-Mn in the structure of the coating of rutile electrodes for hardfacing, on the operational behavior (arc stability). For this, three variants of electrodes with similar chemical composition are elaborated in the metallic core and the coating, differentiating only in the relative position that occupies the alloy charge (C-Cr-Mn) in the structure of the coating: internal, external and homogeneous. For the development of the research a completely random design is used. The operative characterization of the electrodes is performed in terms of the arc stability. In conclusion, it can be seen that the position of the alloy load influences the operation behavior (stability of the arch). The variant of internal alloy charge in the coating presents the better arc stability performance.

The Effect of Microstructural Imperfections on Corrosion Fatigue of Additively Manufactured ER70S-6 Alloy Produced by Wire Arc Deposition

This study aims at evaluating the effect of microstructure imperfections on the corrosion fatigue performance of an ER70S-6 alloy produced by wire arc additive manufacturing (WAAM) process, in a 3.5% NaCl solution. For reference, a regular ST-37 alloy with relatively similar chemical composition was considered as a counterpart alloy. This was justified by the fact that the ER70S-6 alloy is usually used for conventional welding of ST-37 steel. The results obtained indicated that while the ST-37 alloy exhibited fatigue strength of 240 MPa in the corrosive solution, the additively manufactured ER70S-6 alloy showed fatigue strength of only 140 MPa. These differences were related to microstructural imperfections that are inherently produced during the WAAM process.

Experimental Study on Carbonization of Magnesium Slag Cement

Magnesium slag is a kind of industrial waste with the similar chemical composition to silicate cements, which is of hydration activity to some extent. However, the hydration activity of magnesium slag is much lower than that of traditional silicate cements. Through the method of carbonization, this experiment enhanced the hydration activity of magnesium slag, so that the strength of magnesium slag products can meet the requirements of structures together with certain mechanical and physical properties as well.

Creating artificial Rhino Horns from Horse Hair

Demand for rhino horn is driving poaching with devastating effect for the few individuals left of the few species surviving from this once numerous, widespread and cosmopolitan clade of pachyderms. We bundled together tail hairs of the rhino’s ubiquitous near relative, the horse, to be glued together with a bespoke matrix of regenerated silk mimicking the collagenous component of the real horn. This approach allowed us to fabricate composite structures that were confusingly similar to real rhino horn in look, feel and properties. Spectral and thermal FT-IR, DSC and TGA analysis demonstrated the similar chemical composition and thermo-mechanical properties between the natural and the faux horns.

Effect of boron microaddition on hardenability of new-developed HSLA-type steels

Purpose: The paper presents the results of investigations on the effect of 0.003% boron microaddition on the hardenability of new-developed HSLA-type steels. In order to prevent the binding of the boron microaddition with nitrogen in BN nitrides, Ti microaddition at concentrations of 0.033% and 0.028% was also added into the tested steels. Design/methodology/approach: Evaluation of hardenability of the investigated steels was carried out on the basis of the Jominy test and the analytical method, according to the ASTM 255-89 standard, taking into account the effect of the boron microaddition. Additionally, developed of the CCT-diagram of investigated steel. A DIL 805A/D dilatometer with a LVDT-type measuring head was used to carry out the dilatometric test. Findings: Microaddition of boron, introduced into steel in a concentration of 0.003% along with Ti microaddition shielding (in concentration of 0.033% in steel A and 0.028% in steel B), advantageously improves hardenability. This is reflected in calculated ideal critical diameter DIB, which is equal 163 mm for steel A and 155 mm for steel B. The form of curves of phase transformations of supercooled austenite is typical for steels with microaddition of boron, with similar chemical composition. Research limitations/implications: Due to similar chemical composition of investigated steels, the kinetics of phase transformations of austenite, supercooled under continuous cooling, was determined for steel B containing 0.28% C, 1.4% Mn, 0.3% Si, 0.26% Cr, 0.22% Mo and Nb, Ti, V and B microadditions at 0.027%, 0.028%, 0.019% and 0.003% respectively. Practical implications: Tested steels have high hardenability and show the full usability for production of forged parts with the method of thermomechanical treatment, i.e., hot- deformed in the temperature range adjusted to the type of microadditions added to steel, with direct quenching of forgings from finishing forging temperature. The results of the tests may be useful for developing the parameters of heat treatment and thermomechanical treatment of investigated steels. Originality/value: The hardenability of new-developed HSLA-type steels was determined.

Comparison of properties of cutting edges made of HSS obtained by conventional methods and in powder metallurgy process

Selected fragments of investigations of technological and functional properties of cutting edges made of conventional and sintered high speed steel with similar chemical composition are presented. Investigations of technological and functional properties have comparative character and concern among other things estimation of chemical composition, hardness, structure and durability during toughening steel machining.

Effect of chain microstructure on self-assembly and emulsification of amphiphilic poly(acrylic acid)-polystyrene copolymers

In this study, a series of random copolymer poly(acrylic acid-co-styrene) (P(AA-co-St)) and block copolymer poly(acrylic acid)-b-polystyrene (PAA-b-PSt) with similar chemical composition but different chain microstructure were synthesized.

CHEMICAL COMPOSITION AND HYDRAULIC CONNECTIVITY OF SPRINGS IN THE SOUTHERN SLOPE OF MERAPI VOLCANO

Springs are easily found in the southern slope of Merapi volcano, Sleman Regency, Yogyakarta Special Province, Indonesia. Springs origins on this location are commonly related to the existing of Merapi Aquifer System, but importance question of all these springs are hydraulic connectivity among them. In response to the issue, the objective of this research is to determine hydraulic connectivity of springs based on their chemical composition. To answer the objectives, measurement of spring discharge and physicochemical properties of spring’s water and sampling of selected spring’s water were conducted on this research in the study area. Water chemistry composition was classify by Kurlov formula and displayed by Fingerprint diagram and Composition diagram. Results show that the chemical compositions of most all spring samples are almost similar and does not significantly different for most properties from upstream to downstream, which are Na–Ca–HCO3 water, only one spring of Umbul Jatiningsih spring had different chemical composition of Ca–Na–Mg– HCO3 water. Based on the Fingerprint diagram and Composition diagram evaluation, the spring’s water can be differentiated into three groups. Group 1 consists of ten springs which have similar chemical composition of Na–Ca–HCO3 and with electrical conductivity ranges between 150 to 200 mS/cm. Group 2 consists only one spring “Umbul Pajangan” which contain similar chemical composition to Group 1 but has significantly higher ions concentration (EC value about 400 mS/cm) and Group 3 consists also only one spring “Umbul Jatiningsih” which has significantly different ionic composition with Group 1 and 2. Regarding on this condition, it can be concluded that Group 1 spring is hydraulically connected and relate to the shallow aquifer system of Merapi Aquifer System. In other side, water of spring “Umbul Pajangan”possibly comes from deeper aquifer system of Merapi Aquifer System and this argument is supported by the spring discharge evaluation. Finally, spring “Umbul Jatiningsih” is originate mainly from different aquifer system of porous limestone aquifer. Keywords: Merapi aquifer system, spring, chemical composition, geological condition