Homogenization Modes Effect on Mechanical Properties and Corrosive Characteristics of the Rolled Products from Al-Mg (1570) Aluminum Alloy with Addition of Scandium and Zirconium

Objective of the study: study of various homogenization modes effects on mechanical and corrosive properties of rolled sheets from Al-Mg system alloy 1570 with additions of zirconium and scandium transition metals. The sheets were produced in laboratory conditions from the ingot, cast in production DC mold based on the commercial production practices and treatment modes. 4 homogenization modes, 2 tempers H12 and H321, and several modes of stabilization annealing in the temperature range from 240 °C to 325 °C have been reviewed. The samples have been comprehensively examined using optic and electron scanning microscope, mechanical properties were achieved by break test in compliance with ISO 6892-1, corrosion was examined using ASTM G66 and G67 standards. The curve of 1570 alloy sheets softening as the function of annealing temperature was constructed. It was demonstrated that the increasing temperature effect during homogenization leads to strength properties decrease and corrosion resistance improvement due to interdendritic segregation elimination. Among analyzed homogenization modes, 360 - 380 °C - 6 h mode is established as the most practical, and the sheets. produced without stabilization annealing, occurred to be the most resistant to exfoliation corrosion. The sheets, subjected to annealing at 260 °C - 2 h, show no traces of layer corrosion, but have pit corrosion locations rated as «PC» based on ASTM G-66 classification, such rating is unacceptable for the manufacture of products for use in the marine environment.

Solid-Phase Reduction and Separation of Iron and Phosphorus from Manganese Oxides in Ferromanganese Ore

The possibility of joint solid-phase reduction of iron and phosphorus from ferromanganese ore has been experimentally confirmed. Solid-phase reduction was performed at a temperature of 1000°C and exposure time of 2-5 hours, in a CO atmosphere, also produced the separation of the reduction products by melting. The distribution of iron and phosphorus was studied using an electron scanning microscope. The phase analysis of the samples was studied using a Rigaku Ultima IV X-ray diffractometer. The results were processed using the "Match" software. Reducing roasting in a CO atmosphere provides a transition from the oxide phase to the metallic phase of only iron and phosphorus without loss of manganese, thus increasing the concentration of MnO oxide in the residual oxide phase of the ore.

Pre-Crystallization Criteria and Triple Crystallization Kinetic Parameters of Amorphous-Crystalline Phase Transition of As40S45Se15 Alloy

This framework focuses mainly on a detailed study of the pre-crystallization criteria that characterize the As40S45Se15 glassy alloy in various heating rates ranging from 5 to 40 (K/min.) by DSC thermo-grams in the range of (300-575 K). These criteria aim to clarify the relationship of the tendency of glass-forming by the heating rate for the investigated glassy alloy. As well, the present framework demonstrates the criteria of thermal stability. Continuously, the various nucleation and growth pathways. The transformation in activation energy with the volume of the crystalline portion was deduced and, through this, we were able to determine the surface resistance of the analyzed bulk alloy in the crystallization region. The crystalline structure of the study sample was recognized by X-ray diffraction (XRD) and electron scanning microscope (SEM).

Scanning Electron Microscopic Evaluation of Marginal Adaptation of Three Endodontic Sealers: An Ex-Vivo Study

Introduction: To avoid the entry of micro-organism or their products, sealer should completely adapt to the root canal wall so that no gaps will be present. AH plus is the most routinely used sealer. EndoRez is methacrylate resin-based self as well as light cured sealer. Endosequence BC RCS is the recently introduced bioceramic based sealer. Aim: To evaluate the marginal adaptation of Endosequence BS RCS, EndoRez and AH plus as a root canal sealer to root dentin under electron scanning microscope. Methods: Total 75 freshly extracted permanent maxillary central incisors with single canal were included in this study. All the teeth were decoronated till twelve millimeter and access cavity was prepared. All the teeth were prepared with rotary protaper till# F3 with intermediate copious irrigation with 3% sodium hypochlorite and 17%EDTA.Teeth were randomly divided into three groups according to sealers and were obturated- Endosequence BC RCS, Ah Plus and EndoRez. Access cavity was restored with glass ionomer type II in all the groups. After seven days, teeth were vertically sectioned and evaluated under electron scanning microscope for marginal adaptation. Results: Marginal gaps were present in all groups. Maximum number of gaps were present in Ah plus group. Endosequence BC RCS group showed least number of gaps. Discussion: Marginal adaptation of sealer depends upon the properties like flow, viscosity, presence or absence of smear layer etc. Better adaptation of Endosequence BC RCS to root dentin is due to formation of mineral infiltration zone which results in formation of calcific tags in dentine. Conclusion: Within the limitation of present study, newly introduced Endosequence BC RCS showed better marginal adaptability to root dentine. Further studies are required to evaluate and corelate these findings with other properties of these sealers.

The usefulness of Electron Scanning Microscopy in the evaluation of bone structure surfaces and selection of alloplastic materials in facial skeleton loss reconstruction

Introduction: Functional and aesthetic problems can arise even from small losses created in the facial skeleton. Injuries and oncological surgeries are the most frequent causes of these losses within the facial skeleton. Advances in surgical interventions have allowed for ever-increasing degrees of resections, increasing oncological radicality as well as treatment effectiveness, providing the patient with the chance for a longer life. However, this subsequently requires the use of even more advanced reconstruction techniques in order to restore quality of life and comfort to the patient, as well as enable their return to professional and social activities. The necessity of reconstructive surgery applies not only to patients with cancer, but also to patients with impaired or failing sensory and organ function as a result of inflammatory conditions, injuries, or non-oncological surgeries. There are many available reconstruction procedures, which depend on the location of the loss, the type of tissue lost, the degree of loss and patient-dependent factors. Materials used in reconstruction surgeries may include the patients’ tissues when available, and artificial reconstruction materials otherwise. Material and methods: The analysis involved fragments of bone tissue removed during surgery. Due to the nature of the medical procedure and the inability to replant the tissue, it was regarded as medical waste. The preparations used were observed under an optical microscope and an electron scanning microscope, and a chemical analysis was performed. The chemical composition of samples was analysed using a low vacuum detector (LVD) at an accelerating voltage of 15 kV and 10 kV and at a spot size of 4 and 3.5. The observations were performed in a secondary electron (SE) detection system. Results: Observation of parameters under an optical microscope and of images obtained using an electron scanning microscope showed the presence of typical, compact bone tissue with varied surface shapes in each case (various degrees of unevenness and porosity). Chemical composition analysis confirmed the presence of compounds from the CaO-P2O5-H20 system. The Ca/P (calcium/phosphorus) ratio obtained from the chemical analysis varied from 1.33 to 2.1, and indicated a varied morphology of calcium phosphates forming the bone structures of the facial skeleton. Conclusions: 1. Calcium phosphates are characterised by excellent biocompatibility because of their chemical affinity to bone, and are ideal for the reconstruction of bone losses within the facial skeleton. 2. Biodegradable polymers have the highest functional potential among several groups of biomaterials used in tissue engineering because of their ability to be tailored individually, in addition to their high biocompatibility.

Preparation of Terminalia catappa Shell Based Activated Carbon by Microwave Assisted Chemical Activation

Activated carbon was prepared from Terminalia catappa shells using microwave asissted KOH activation. The ratio of mass percentages of Terminalia catappa and KOH were 4:1, 4:2, and 4:3. Terminalia catappa based activated carbon was prepared by KOH activation at the room temperature for 24 hours and followed by microwave irradiation at the out put power of 630 Watt for 20 minutes. The physical properties of activated carbon i.e. surface morphology, micro structure, and BET surface area were characterized by electron scanning microscope, X-ray diffraction and N2 adsorption-desorption isotherm at 77K, respectively. The highest BET surface area was 312 m2/g with adsorption of activated carbon towards methylene blue by 84.4 mg/g. The BET surface area was directly correlated with the stack height (Lc) of the activated carbon.

Enzymatic Synthesis of KDN-Containing Sialylated Lactuloses and their Bacteriostatic Activities on Staphylococcus aureus

Sialic acids are found in various biological tissues and are known to play important roles in many biological processes. However, many sialylated oligosaccharides are not adequately available to study their biological functions and potential uses. Herein, we reported an efficient synthetic approach to obtain sialylated lactulose containing deaminoneuraminc acid (KDN). Both KDNα2,3lactulose and KDNα2,6lactulose were synthesized via one-pot multienzyme sialylation system. The bacteriostatic activities of these two sialylated lactuloses against Staphylococcus aureus (S. aureus) were analyzed by using approach of optical density OD600 measurements. In addition, integrity of cell membrane of S. aureus was examined by fluorescence analysis, protein leakage quantification and electron scanning microscope (SEM). The results showed that the maximum inhibition ratios of KDNα2,3lactulose and KDNα2,6lactulose within the first 10 h was up to 34.33% and 32.18%, respectively. KDNα2,3lactulose displayed slightly better inhibition against the growth of S. aureus than that of KDNα2,6lactulose. The addition of KDNα2,3lactulose and KDNα2,6lactulose caused a significant decrease (pandlt;0.05) in fluorescence intensity compared with control to 47.05and#177;3.06% and 51.16and#177;2.40, respectively, indicated that those two sialylated lactuloses had some extent interference with nucleic acids synthesis or caused decomposition of nucleic acids in S. aureus cells. Fluorescence microscopy results showed that S. aureus of KDNα2,3lactulose and KDNα2,6lactulose group present obvious loss of viability. The leakage amount of proteins in S. aureus treated with KDNα2,3lactulose and KDNα2,6lactulose increased by 223 μg/mL and 205.4 μg/mL, respectively. The morphological alterations on the cells observed by SEM confirmed that KDN-containing sialylated lactuloses possessed antibacterial activities. In a word, KDN-containing sialylated lactuloses have certain effects on inhibiting the growth of S. aureus.

A concept of control of processes of vanadium, niobium and titanium carbonitrides forming by consecutive alloying

Base on laboratory and industrial experiments, as well as subsequent studies of the microstructure of steel samples alloyed with a certain sequence by vanadium, niobium, and titanium, a concept including compliance with the order of those microalloying elements introducing into steel developed and justified. According to the concept, the sequence of introduction is determined by the difference in the degree of their thermodynamic affinity to the nitrogen and carbon dissolved in the steel.Investigations of the microstructure of experimental microalloyed samples by an optical microscope, with a magnification x250, showed the most significant grain refinement with a consecutive additive – first vanadium with niobium and after 10 minutes of holding – titanium.The efficiency of the developed alloying method for the advanced formation of vanadium and niobium carbonitrides was evaluated by studies with the Mira3 Tescan electron scanning microscope having an X-ray energy dispersive microanalysis system X-Act (Oxford Instruments). When studying the compositions and the form of carbonitrides discovered in steel samples alloyed with a different sequence of additives, it was established, that during simultaneous additive of titanium, vanadium and niobium into steel, titanium carbonitrides account for a majority, while vanadium and niobium carbonitrides are not actually formed or are represented by single inclusions. Conversely, in steel samples alloyed with a consecutive additive to steel, first vanadium with niobium and later titanium, carbonitride of vanadium and niobium inclusions prevail. In this case, titanium carbonitrides are represented only by single and fine inclusions. Thus, first introducing of vanadium and niobium, allows them to react fully with stoichiometrically insufficient concentrations of nitrogen and carbon, ahead of the formation of titanium nitrides.Based on the results of the research in JSC “ArcelorMittal Temirtau”, using the developed concept of consecutive alloying by carbonitride-forming elements, the technology of 09G2FB grade steel production with a ferrite-bainite structure developed and implemented, fully meeting API Spec 5L requirements for steel of strength category X80.

Instability of Plastic Deformation in Low-Alloy Copper Alloys

The purpose of this paper is to determine the influence of temperature of plastic deformation on the structure and mechanical properties of copper alloys of the types CuCo1NiBe (CCNB), CuCo2Be (CB4), CuNi2SiCr (CNCS), CuNi1P (CNP) and CuCr1Zr (CW106C) applied on electrodesduring a tensile test. Tensile tests were carried out on polycrystalline samples of above mentioned alloys, which confirmed the presence of inhomogeneous plastic deformation in specified temperature ranges for each alloy. The tensile test of the investigated copper alloys were realized in the temperature range of 20÷800 °C with strain rate of 1.2•10-3s–1 on the universal testing machine. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope. Performed experimental studies have proven that analyzed structural factors, in a range of investigated strain conditions at elevated temperature, significantly influence the phenomenon of the Portevin Le Chatelier (PLC) type instability of plastic strain, revealed in low-alloy copper alloys. Moreover, it was found that the impact of examined factors on the PLC effect should be considered comprehensively, taking into account their synergic interactions.

Molecular-field Molecular-field Study on Sn Substituted Yttrium Iron Garnet

Samples with the compositions Y2.9Ca0.1Fe4.9Sn0.1O12 and Y3Fe4.9Sn0.1O12 were prepared by using a sol-gel technique. The influence of the substituted non-magnetic cations with different valences in the structural and magnetic properties was studied. X-ray diffraction and field-emission electron scanning microscope techniques were used to study the crystal structure and morphology. Magnetization curves in fields up to 10 kOe and in temperature range from 80 K to 570 K were measured by means of a vibrating sample magnetometer. Saturation magnetization as a function of temperature of the two samples was analyzed based on the molecular-field theory from that models for site occupancy and valence states of cations in the crystal structures were derived.