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The intention of this paper is to review of some recent innovative novelties about paper and board pigment coating raw materials. First an overview is given of “traditional” coating raw materials and the coating process. Then new starch based pigments and binders as well as novel plastic pigments are reviewed regarding their effect on coated paper properties. Finally it is concluded that further innovations and research are needed.

Present paper reports investigations carried on corrosion behaviour of mild steel in effluents collected from paper mill treatment plant. For this purpose, effluent was collected from after primary and secondary treatment stages. Mild steel samples were exposed to these effluents for duration of six months. The corroded samples were analysed for weight loss and extent of localised corrosion. Electrochemical polarization tests like open circuit potential (OCP), tafel plot and anodic polarization were also performed to estimate corrosion rate, polarization resistance and localized corrosion parameters in the studied system. The extent of corrosion attack has been correlated with effluent parameters namely pH, electrical conductivity (Ec), total suspended solids, total dissolved solids, chemical oxygen demand, biochemical oxygen demand, chloride content, colour and sulphate.

Organosilicon compound are widely used in pulping and papermaking industry. The quality and capability of paper sheet are distinctly affected by the use of organosilicon. The application of organosilicon used as softening agent, defoamer agent, strengthening agent were introduced one by one in this paper.

The effect of ZnO dosage, iron remover and the time duration of neutralization and iron-precipitation on iron removal percentage was investigated to find out the optimal parameters in the technique of ZnO pressurization, neutralization and iron removal, and the residual acid from pressurization lixiviation and neutralization was assayed by using ZnO ore to neutralize and remove iron from lixiviated mineral pulp containing residual acid 20 g/l by simulation of Zn concentrate pressurization and lixiviation in a 2 L autoclave, in order to simplify Zinc pressurization process. The result showed that when Zn lixiviation percentage is higher than 98 %, up to 99.74 % of iron in the lixiviation fluid could be precipitated and the lixiviated fluid contains iron at the level of 20 mg/l, meeting the requirement on pre-purification fluid. Keywords: Zinc Sulfide Concentrate; Pressurization and Lixiviation; ZnO Ore; Neutralization and Iron Precipitation

In this paper, advanced Fenton-hydroxide precipitation process was proposed to remove synthetic wastewater containing CrEDTA. This process can not only remove chromium, but also reduce COD values. Parameters affecting chromium removal are discussed. At optimum conditions, the chromium removal efficiency attained 87%. Advanced Fenton-hydroxide precipitation process appears a promising and effective method for the treatment of strong stability complex heavy metal containing wastewaters.

Cobalt, having many diverse and critical uses, is an essential metal in today's society. However, the recovery of cobalt is difficult due to its associated mineral characteristics. A biohydrometallurgical process has been developed for cobalt recovery from low grade refractory carrollite. After direct oxidation for 6 days, 96.51 % Co and 26.32 % Cu were extracted from the ore using a pulp density of 10 %. The bioleaching solution contained 22.62 gL-1 ferric iron while the concentration of cobalt was only 0.83 gL-1. Therefore, a goethite deironization process was then conducted. Different conditions, such as pH value, temperature, standing time and oxidant concentration were studied in detail. The results showed that when the pH value was 4.0, oxidation temperature was 70 °C, standing time was 1 h, and oxidant concentration was 8%, then the iron removal and the loss of cobalt were 99.9 % and 0.5 %, respectively. The goethite precipitate had good filterability. The sum recovery of cobalt in the whole extraction process attained more than 95 %. The biohydrometallurgy process for the recovery of cobalt has economic and environmental advantages over the other methods.

Rapid technological advancement and the relatively short life time of electronic goods have resulted in an alarming growth rate of electronic waste which often contains significant quantities of toxic and precious metals. Compared to conventional chemical recovery methods, bioleaching has been shown to be an environmentally friendly process for metal extraction. In this work, gold bioleaching from electronic scrap material (ESM) was examined using batch cultures of the bacterium Chromobacterium violaceum which produces cyanide as a secondary metabolite. Gold was bioleached via gold cyanide complexation. The ESM was pretreated using nitric acid to dissolve the base metals (mainly copper) in order to reduce competition for the cyanide ion from other metals present in ESM. ESM was added to the bacterial culture after it reached maximum cyanide production during early stationary phase. Spent medium bioleaching using bacterial cell- free metabolites showed a higher gold recovery of 18%, compared to that of two-step bioleaching of 11% at 0.5% w/v pulp density of ESM. Gold bioleaching was further enhanced to 30% when the pH of the spent medium was increased to shift the equilibrium in favor of cyanide ions production. Spent medium bioleaching of pretreated ESM yield a higher gold recovery compared to two-step bioleaching at a pulp density of 0.5% w/v.

The mining districts located in the western mountain range in the south of Ecuador have gold minerals with refractory characteristics, which do not allow gold recovery by traditional methods used in Ecuador. Therefore, it is necessary to apply some technology that permits to obtain greater metal recovery. Bio-oxidation, as treatment of refractory ores that contain low grade of gold, offers an economic and sustainable alternative for this purpose. The objective of this research was to evaluate the effect of particle size, pulp density and concentration of inoculum and inducer (Fe+2) on the bio-oxidation of refractory gold minerals in order to maximize gold recovery of the bioleached minerals by means of a cyanidation process. The microbial consortium used in this work was collected and isolated from the Portovelo mining district corresponding mostly toAcidithiobacillus ferrooxidansandLeptospirillum ferrooxidansspecies. The Eh, final concentration of ferric ion, total iron and sulfates were measured. Finally, the bio-oxidized material was tested using cyanidation to determine the gold recovery. The results after the cyanidation tests showed that the highest gold recovery was obtained when the bio-oxidation step was conducted with 68-91 µm particle size, 15% pulp density, 20% v/v inoculum and 2 g/L of Fe2+as inducer. At those conditions, gold recovery was 68% compared to 26% obtained when no bio-oxidation step was performed, demonstrating that this process was favorable compared with traditional gold recovery processes

The viscosity of Pulp will affect the grinding rate directly, Elevated temperature, the slurry viscosity reduced. In order to study the effect on the grinding rate of temperature, we did the experiment by only changing the temperature, and three groups of contrast test was carried out. The results show that the grinding rate is improved obviously, when the grinding temperature increases from 16 °C to 42 °C.

Bioleaching of the copper flue dust emanating from smelters at Sarcheshmeh Copper Complex has been studied. At the present, the dust is sent back to the smelter, which reduces its efficiency. In this study, a continuous system including a feed tank and two-stage aerated stirred tank bioreactors was established. Mixed mesophile bacteria with different amounts of the dust containing 35% of copper mainly in the form of sulfide minerals were used. The effects of pulp densities, residence times and temperatures on the final copper recovery and redox potential were experienced. Despite the copper concentrates bioleaching, the process of dust bio-treating was net acid consuming. Lower pulp densities resulted in a stable redox potential in both reactors. However, increasing the pulp density to 7%, was created an unstable redox potential in the first bioreactor especially at lower temperatures. Final copper recoveries were calculated for pulp densities of 2%, 4% and 7%, were 91.8%, 90.3% and 87.6% with residence times of 2.7, 4 and 6 days respectively. The promising results indicated that bioleaching is a feasible process that can be applied to copper flue dusts.

Bagasse, a fibrous residue from sugarcane juice extraction, was used as a reducing agent to roast low-grade pyrolusite in N2. The roasted ore was further leached using sulfuric acid, to convert manganese oxide in the ore to manganese sulfate. The effects of weight ratio of bagasse to manganese ore, roasting temperature, roasting time, leaching temperature, leaching time, stirring speed and sulfuric acid concentration on the leaching recovery of manganese were investigated. Optimal conditions were determined to be a bagasse to manganese ore weight ratio of 0.8:10, roasting temperature of 500°C for 40 min, leaching stirring speed of 100 rpm, sulfuric acid concentration of 3 mol•L-1 and leaching temperature of 50°C for 40 min. The leaching recovery rate of manganese was up to 97.8% at the optimal conditions.

Titanium oxide is believed as one of the key factors that influence the excellent corrosion properties as well as biocompatibility of titanium alloy. In the present research, thermal-electrochemical anodizing processes were performed in order to form thick layer of titanium oxide on titanium alloys (Ti6Al4V) surface. Oxidation temperature, blasting and anodizing voltage were selected as the evaluated parameters process at the present study. It was observed that temperature plays important role in the formation of oxide layer, where the thickness of the oxide increases significantly as temperature increases. However, for the case of oxide layer formed by thermal oxidation at temperature of 950oC, oxide layer on the non-blasted sample become easily peel off, whereas oxide layer on the blasted sample shows good adhesion properties. In addition, oxide layer on the blasted samples also have thicker layer as compared with oxide on the non-blasted sample. On the other hand, it was observed that further oxidation by anodizing at 43V and 63V create finer oxide layer by the filled up of porosity on the existing oxide layer. However decreasing of oxide layer thickness was also observed after anodizing, which is predicted due to the breaking up the outer oxide layer during anodizing process.

For the Mo-Ni ore that mineral composition is complex, and the grade is relatively low, the flotation’s effect is not good in advance for enrichment, because of the influence of fine grained level gangue minerals. The small diameter hydrocyclone were used to pre-discard tailings, with the best pulp density and feed pressure, the rate of throwing is the 30%, and then the flotation obtained a good beneficiation index. The crude ore that contains Mo 2.04 %, Ni 1.87 %, through the closed-circuit test won a concentrate that the grade of Mo is 8.94 % and the recovery is 91.86 %, the grade of Ni is 6.75 % and the recovery is 86.79 %. Compared with the single flotation process, it improved the flotation effect and the enrichment ratio of Mo Ni, and realized the efficient enrichment of Mo-Ni.

In this experiment, the copper-containing wastewater was adsorbed by HAP which was prepared by high temperature calcination after high temperature cooking fish scales. By the single factor experiments and orthogonal experiments, the optimal conditions were as follows: the initial concentration of copper ion was 200mg/L,the dosage of HAP was 0.2g,the reaction time was 30min,and pH was 5. The maximum removal efficiency was 98.23%.

Kaolin is a mineral composition of water cut aluminum silicate collection of words, used widely. But since most kaolin contain quality score 0.5% ~ 3% of iron oxide or hydrogen ferric oxide, restricted its use. With reduction and complexation method to kaolin bleach, which can effectively reduce the content of iron in the clay. The low pH in with organic acid(citric acid, acid, oxalic acid, also sugar) refined bleached high content of coal kaolin ferric oxide. The results show that, citric acid and also the sugar acid in iron effect is poor, does not meet the industrialized production, oxalic acid can remove kaolin can dip in iron, when pH lower than 1.2, the temperature of 80 °C on the bleaching, white degree of more than 80%, to adapt to the industrial application of coal kaolin basic conditions. At the same time, because of the difference of shading minerals, different sources of kaolin bleaching and the white degree stability condition is different, the actual production of should according to the specific of the sources, after the test to be sure.

Chinese fir (Cunninghamia lanceolata Hook.) and Mongolian Scots pine (Pinus sylvestris Linn. var. mongolica Litv.) with dimension of 19.019.0450.0 mm were treated with two concentrations of amine copper quat-type D (ACQ-D) solutions (0.5%, 1.0%) respectively and post-treated with three different methods including humidity chamber, drying oven and hot water bath. The effects of these variables on copper leaching from ACQ-D treated wood were investigated according to the leaching test of AWPA E11. The results showed that post-treatment could improve the leaching resistance of ACQ-D treated wood effectively compared to the specimens those were leached immediately after impregnation. After some promising post-treatments, copper leaching from the treated wood was not only associated with the joint effects of retentions, wood species and different locations in the treated wood, but also influenced by the special fixation mechanisms in different post-treatments.

This work compares gold bioleaching from e-waste containing gold and copper by Chromobacterium violaceum and Pseudomonas fluorescens. The effect of pulp density (ranging from 0.5 to 8%w/v) was examined. Although C. violaceum produced more cyanide than P. fluorescens in the absence of e-waste, P. fluorescens showed higher growth rate, cyanide production and gold leaching efficiency at all pulp densities. Pretreatment with biooxidation of the e-waste using Acidithiobacillus ferrooxidans resulted in the removal in excess of 80% of the copper present in the waste, and increased the gold/copper ratio in the residual solid. Bioleaching the biooxidised e-waste significantly improved gold recovery, especially by C. violaceum, particularly at high pulp density. For example, at pulp densities of 2 and 4% w/v, gold recovery from non-biooxidzed e-waste was 0.22 and 0.14% respectively. Higher gold recovery, at 8%, was obtained for bioleaching of the biooxidised e-waste at both these pulp densities. The ratio of gold/copper in leachates after bioleaching of the biooxidized e-waste was also found to be increased.

Identifying influential factors in the bacterial leaching of nickel laterites using a mixed culture of chemolithotrophic micro-organisms was explored using the approach of statistical design of experiments. In a series of experiments, pH, particle size, pulp density, type of substrate and inoculum size were statistically combined using a quarter fractional factorial designs 2 5−2 III and tested for their influence on nickel recovery using chemolithotrophic microorganisms. The results indicated that inoculum size was not statistically significant while the rest of the factors were statistically significant. Under the ranges studied the interaction between the variables was found to be weak. The results also showed that recovery was maximized at low pH and low pulp density. In the range studied, particles of less than 38μm had a negative influence on nickel recovery. Sulphur substrate also showed better effects than pyrite.

In this work, bioleaching of iron from a kaolin sample was carried out using two different strains of Aspergillus niger, and the effects of strain type, pulp density, and addition time of clay on the iron removal were investigated using a full factorial design. It is concluded that strain type has the most significant effect on the iron removal. Also, the highest removal extent was 42.8% that was achieved by using the strain isolated from pistachio shell at the pulp density of 20 g/l, when the clay was added at the beginning of the experiments. The results showed that for the experiments in which the clay was added in the first day of cultivation, the average organic acids concentration (citric acid: 5.6 g/l, and oxalic acid: 4.54 g/l) were higher in comparison to those experiments in which the clay was added in the third day (citric acid: 5.25 g/l, and oxalic acid: 2.87).

The paper present some general aspects regarding results obtained by ISIM Timișoara at FSW of steel alloys, with wide use in important industrial fields. The paper also contains information on own contributions of ISIM Timișoara in the field of FSW.Until the present, ISIM Timisoara has responded to some specific requests from the industry, for applying of the FSW process to light alloys and industrial copper Cu 99.The paper presents some general elements regarding the results obtained to welding steels having wide use in industry and which can substantiate industrial applications.The experimental welding programs were developed using the techniques of application of the FSW process, made by ISIM Timisoara: FSW welding machine, welding tools for steels, monitoring systems of the welding process FSW, respectively system for applying of the FSW-TIG hybrid welding process.Sintered tungsten carbide P20S tools with smooth shoulder and pine in 3 constructive variants: smooth conical, smooth cylindrical and pine with four flat recesses (pyramid trunk) were used.It has been shown that the welding tools made of P20S tungsten carbide, with sharp edges, are more resistant and present the best solution for FSW applications.Experimental programs have shown that by observing specific process conditions, the FSW process can be applied with excellent results when welding steel.

The papers aim is to detail temper bead realization, as a possible solution to the removal of heat treatments. Applying temper beads could be a solution for repair, in case surface heat treatments are required, provided they are correctly applied. The paper presents the main ways of applying temper beads, presenting in the same time what the outcomes could be in case of not respecting the prescribed work sequence.

The aim of this paper is to analyse the effect of the pore morphology on microstructural characteristics, mechanical properties and abrasive wear resistance of iron-based alloys subjected to a thermochemical treatment as carburizing in fluidized bed. The starting materials studied in this paper are represented by pre-alloyed iron base powder obtained by powder metallurgy (P/M) route. The powders were produced by water atomization with different particle sizes (< 45, 45-63, 63-100, 100-150, >150 μm). The raw powders have been mixed with 1% zinc stearate as lubricant and uniaxially compacted into cylindrical specimens at room temperature at 600 MPa. The disc dimensions are 8 6 mm. The green compacts were sintered at 1.150 °C for 90 minutes in a laboratory furnnace. After sintering, a thermochemical treatment was applied. The parameters for the carburizinng in fluidized bed are: temperature of 930 °C and time of 45 minutes. The microstructural characterization was carried out using optical microscopy. The porosity of studied samples were analyzed acording to their microstructural characteristics and chemical composition. The mechanical properties and abrasive wear of the sintered and thermochemical treated samples were evaluated. A correlation between porosity, mechanical properties and abrasive wear was established.

Our paper aims to develop new materials in view of meeting the requirements of reducing pollution in steel plant production. The concept of composite with technological role based on creating new complex metal matrix with solid particles in granular form has multiple purposes, among which we mention reduction of pollution in steels department and reduction of economic losses through recovery and reusing of granular ferroalloy particles. This paper proposes a method and technology for obtaining composite materials using A6061 aluminium alloy as matrix and granular SiC disperse particles. Due to its high carbon content (30%), the composite can be used as complex deoxidiser and decarburization agent in steel elaboration. For the preparation of these composite A6061/SiC, the Stir Casting Vortex method has been considered in order to ensure a high embedding yields in granular state and it was with conducted a rigorous control of process parameters (temperature, speed of rotation, improved ways of introducing particles in granular state). The obtained composites have been characterized for morphology, chemical composition and structural analysis by scanning electron microscopy with energy-dispersive X-ray spectroscopy and X-ray diffraction methods

This paper presents a review of high temperature ceramics research for aerospace applications. Following a brief historical perspective, the paper reviews the effort to toughen ceramics for high temperature structural applications. These include: efforts to toughen zirconia-based ceramics, aluminum oxide, silicon carbide, silicon nitride, molybdenum disilicide and zirconium diborides and carbon-based composites. The development of thermal protection systems is also reviewed within the context of thermal barrier coatings (TBCs) and thermal protection systems for space vehicles. The paper concludes with a final section in which the implications of the results are then discussed for the thermostructural applications of ceramics in aerospace structures.

The paper presents results of the researches conducted upon the use of the arc-air gouging process with coated electrodes, in comparison with the plasma gouging process, in case of the welded structures. The paper aims at submitting the arc-air gouging technologies with electrodes and the plasma gouging technologies. The research consists in gouging a structural steel, of the quality S275JR and in comparing the surfaces obtained by the enumerated processes. The obtained samples will be analyzed in terms of microstructure, macrostructure, hardness of the thermally influenced area, hardness of the gouged area.The gouging process is based on melting the raw material, with an electric arc achieved between an electrode and the raw material; and on removing the melt material with a compressed-air jet, in the case of the arc-air gouging and plasma gouging. The gouging with coated electrode is different, given that it requires special electrodes, with thick flux cover, in order to generate an electric arc and a strong gas flux. During the gouging process, the raw material will be oxidized; yet, this does not influence the process. The gouging process can be either manual or automated. In this paper, the manual variant will be submitted, in the case of the arc-air gouging technology and the gouging with coated electrodes; in the case of the plasma gouging, both variants will be submitted.

In this paper is presented an experiment whose aim is to determine the cutting forces that appear when machining Ti6Al4V titanium alloy, in order to optimize its working rate and productivity. This experiment uses carbide coated milling tools for milling titanium alloy. It has studied the influence that milling parameters have upon the three dimensional cutting forces. The equipment which was used included stationary dynamometer for measuring cutting forces, with piezoelectric transducers. The cutting force model is developed in terms of cutting speed, feed rate, axial depth and length of milling (radial depth), with values established according to response surface methodology in intervals from the specialised literature. Titanium alloys are a continuous challenge. This paper is important because is getting relevant results for improving manufacturing efficiency.

This paper presents the results of experimental research on the possibility of using bronze chips recovered from the cutting process of the molded sliding bearings to obtain new sintered sliding bearings. This paper presents the results of experimental research on the possibility of using bronze chips recovered from the cutting process of cast sliding bearings in developing new sintered bearings). The cooper-tin alloys have many applications in the industry and they are usually used as antifriction materials to sliding bearings construction. Chips recovered from cooper-tin resulted from the cutting process were used to obtain metal powders in planetary mills. Recovered powders were then compacted to a unilateral mold and then were applied a sintering cycle in argon. To the obtained samples we applied wear tests in conditions of dry friction to prove the possibility of use as anti-friction material for sliding bearings in similar conditions to those obtained from industrial powders.

Metallic biomaterials are used in various applications of the most important medical fields (orthopedic, dental and cardiovascular). The main metallic biomaterials are stainless steels, Co-based alloys and Ti-based alloys. Recently, titanium alloys are getting much attention for biomaterials because these types of materials have very good mechanical properties, good corrosion resistance and an excellent biocompatibility. The paper contains important information about titanium alloys used for biomedical applications, which are considered the most widely. It is very important to understand the microstructural evolution and property-microstructure relationship in implant alloys. In the present paper, authors present a short literature review on general aspects of promising biocompatible binary Ti-Mo alloys compared with CoCr and stainless steel alloys, as an alternative of the known metallic biomaterials. This alloys show superior mechanical compatibility and very good biocompatibility. The aim of this review is to highlight the mechanical properties for several types of biomaterials, their application in medical field, especially the Ti-Mo group.

The corrosion of steel elements in reinforced concrete can cause considerable damage to civil engineering structures. Early detection of corrosion is therefore very important. Steel in concrete is protected if the concrete pH is higher than 9.6. Carbonated concrete, unfortunately, has a lower pH and this causes that the unprotected steel reinforcement begins to corrode. Nonlinear ultrasonic spectroscopy (NUS) methods shows potential to be very reliable to identify the structure defects in a wide range of materials. These methods are based on the fact that crack-induced nonlinearity makes a sensitive material impairment indicator. This paper describes the ability of one of NUS methods for monitoring steel corrosion in reinforced concrete. It studies nonlinear interaction between elastic waves and structural defects caused by corrosion of steel in concrete. For research we used concrete beams with ten millimetres thick steel rods. These beams were exposed to accelerated degradation by chlorides. The paper presents the initial results of our research.

The thermal cycles simulator of welding is a complex equipment that reproduces in a specimen thermal cycles of the type caused in the HAZ by welding processes.In this paper, it is presented a comparison between the results obtained by welded joints and thermal cycle simulator specimens, from the material P355NH of 22 mm thickness for pressure vessels. Two types of thermal cycle simulator specimens were used: one specimen without post-simulation heat treatment and one specimen with post-simulation heat treatment.For the welded specimens Mn3Ni1CrMo filler material was used.This paper offers information about the impact energy of specific areas of the welded joints, both for butt welding and thermal cycle simulator specimens.A good correlation was observed between the results of thermal cycle simulation with post-simulation heat treatment and the results obtained by welding.

Equal-Channel Angular Pressing (ECAP) is a very interesting method for modifying microstructure in producing ultra-fine grained materials (UFG) and nanomaterials (NM). In the ECAP processing a sample is pressed through a die in which two channels of equal cross-section intersect at an angle of ϕ and an additional angle of ψ define the arc of curvature at the outer point of intersection of the two channels. ECAP is unique because significant cold work can be accomplished without reduction in the cross sectional area of the deformed workpiece. The key feature of ECAP processing is almost as a general rule the die design and manufacture as there is limited knowledge about ECAP and especially about ECAP die design, present paper offering an optimum solution to this problem, applied to multi-pass ECAP processing of an aluminum alloy. In this study a number of three ECAP dies with vertical configuration were considered, thereby combining the ease of execution with a relatively high maneuverability and posing minimum difficulties when extracting samples from the output channel. An optimum solution is also given by the present paper for designing and manufacturing the punches used for pressing the aluminum alloy through the three ECAP dies, minimizing this way the force required for plastic deformation and the power consumption and improving the ECAP process efficiency and stability.

The present paper shows the experimental results obtained on two complex alloys Co-Cr-W-C-Fe-Ni-Si-Mn-Mo and Ni-Cr-Fe-B-Si-C-Co alloys deposited on copper support by welding (TIG). Well - known for their excellent abrasive wear, corrosion and high temperature erosion resistance, these materials were chosen as protective solutions for some highly mechanically and thermally stressed devices, namely the blast tuyeres of blast furnaces. A testing method which simulates as near as possible the real working conditions is the quick thermal shock, consisting in heating at the chosen testing temperature followed by cooling in cool air spray, for 25 cycles. Testing parameters were set according to the blast tuyere device working conditions. In this paper, the coatings microstructure’s comparative changes consequently to quick thermal shock were monitoring, because this affect the device lifetime and mechanical characteristics. The untested samples as well as on quick thermal shocked ones was investigated using X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).

Typical applications of metallic dental materials include metal-ceramic restorations, dental implants or orthodontic systems. Due to their contact with human tissues, corrosion resistance is one of the main requirements for dental materials. In the present paper, the corrosion behaviour in Fusayama Meyer artificial saliva solution (pH=5.2) on a selection of four different metallic dental materials (316 L steel, Au based alloy, cp-Ti, Ti6Al4V alloy) currently used in dentistry were investigated. The metallic dental materials have been investigated in terms of electrochemical analysis, chemical composition, morphology before and after corrosion, wettability and roughness. The results showed a hydrophilic behaviour in the case of Au based alloy, cp-Ti and Ti6Al4V alloy, and hydrophobic for 316L stainless steel. Considering the main electrochemical parameters, the cp-Ti alloy exhibited better corrosion resistance in artificial saliva with pH=5.2, followed by Au based alloy, Ti6Al4V alloy and 316L stainless steel. The main objective of the present paper was to evaluate the corrosion behaviour, as in important factor in the selection of metallic materials used in dentistry.

A spark plasma sintering technique was used to consolidate NdFeB compacts at four different temperatures as 750°C, 850°C, 950°C and 1030°C. The surface of specimens was polished to remove the carbon paper on the surface of NdFeB compacts by using SiC paper for up to #1500 in grit. The polished NdFeB compacts were then magnetized by using impulse magnetizer K-series. In this study, the effects of temperature on the structure and magnetic properties of NdFeB magnet were studied. The results show that depending on the fabrication temperature, the X-ray diffraction patterns of NdFeB compacts are distinct. This suggests that the structure of NdFeB compacts is changed with increase in fabrication temperature. Meanwhile, the remanance Br and energy product BH(max) of NdFeB magnets tend to decrease as fabrication temperature increase.

Development of new steels with higher creep resistance must be based on detailed knowledge of strengthening and degradation processes, structural stability at high temperature exposure and their welding. This paper is concerned with the real weld joint hardness and microstructure of progressive low alloy creep resistance T24 steel. These steel is widely used in many power-plant constructions all over the Europe. Welding the T24 steels components is one of the most important technological procedures. The aim of the performed investigation is to evaluate the hardness and microstructure in the heat affected zone (HAZ) and the weld metal. Results of the secondary hardening in the real weld joints after low temperature post weld heat treatment (460°C/48h) and without post weld heat treatment at service temperature are described in this paper. Obtained results are compared to the hardness values of the weld joint post weld heat treated at recommended temperature (740°C). The microstructure of the real weld joints was analysed by transmission electron microscopy (TEM) in order to identify minority phases - MX nanoparticles and/or coarse (M23C6) particles. Secondary hardening of the not heat treated and low temperature heat treated T24 weld joint was proved.

This paper presents experimental results revealed on the samples type 2024 aluminum alloy used in aeronautics. The results of microstructural and compositional investigations presented in this paper were performed on samples taken from 2024 Al alloy samples produced by ALRO Slatina. The main objective of the investigation is the conformity assessment of alloys in terms of chemical composition with the specifications type of aviation [SAE AMS 47N, EN 515, etc]. It also aims microstructural conformity assessment in terms of the grain and the hardening effects by natural or artificial aging applied by the manufacturer. Adequate characterization of 2024 aluminum alloys type was achieved by combined investigations: (i) Wet Chemical Analysis, (ii) Spectrochemical Analysis and (iii) Electron Microscopy. The main conclusion that emerges from the investigations carried out on aluminum samples revealed that: (a) alloys fits in terms of composition with the standard specification for 2024, in all cases; (b) microstructure vary in fineness of grain, but meets the requirements of aviation rules; the investigated microstructures have been appreciated as adequate of aluminum alloys type "2024".

As one of the key techniques for manufacturing three-dimensional metal microstructure, micro-electroforming processing technology plays an important role in MEMS. Mechanical properties of micro-electroforming Ni have become a new research hotspot. This paper gives a brief overview of micro-electroforming Ni material’s mechanical properties. Due to the complexity and lack of standardization during micro-electroforming process, mechanical properties are found to be dependent on micro-electroforming process parameters and conditions. It is essential to reveal the essence of mechanical properties from microcosmic aspect. This paper briefly summarizes observation tools of microstructure and reviews the relationship of mechanical properties and microstructure. This work lays theoretical foundation for dynamic analysis and calculation of micro-electroforming Ni devices.

This paper presents in detail the laser welding of a new mechatronic component belonging to the pressure sensors made ​​by aluminum alloy AW2007. Due to very high reflectivity of aluminum alloys, fast oxidation, the absorption of gases from the surrounding medium, special difficulties arise at laser beam welding and most situations require appropriate surface pretreatment. Given these issues, the paper present an experimental study on the influence of welding parameters on the seam quality for the aluminum alloy AW2007. In addition of the study regarding the influence of welding parameters, such as, laser power, welding speed, we conducted an analysis on the influence of the initial temperature of the material on the quality of the weld. Besides these aspects the paper presents a constructive solution for a device used to optimize the laser welding process of the sensor.

A new hot stamping process with quenching and partitioning treatment is proposed in the paper. Compared to direct hot stamping process, the microstructures with some retained austenite not only including martensite are formed according to the constrained carbon equilibrium (CCE) model. During the new hot stamping process, tools with high temperature are used to control the quenching temperature (QT) between Ms and Mf, and the partitioning treatment of the part is also implemented in the tools by prolonging holding times. In this paper, different holding times (partitioning times) controlled by servo press, are used to research the influence of partitioning time on mechanical properties.

The paper presents the results of studies the deformation behavior of aluminium alloy D16 by acoustic emission (AE) method. The purpose of this study was to establish the deformation stages and deformation mechanisms at each stage. Studies were carried out on the samples of aluminum alloy D16 (analog 7075). This paper contains a method for the separation of AE signals. The method of AE sources identification based on the the two-parameter distribution analysis (frequency parameter Kfvs energy of AE signals). The frequency parameter Kf is based on wavelet transform of AE signals. Two-parameter distribution allows one to separate the AE signals emitted by dislocations from the signals of micro cracks. The investigation results allowed the various deformation stages to establish by the different types of AE signals. By the AE analysis shows the dislocation mechanism of hardening the aluminum alloyD16. The paper presents the results that characterize the influences of heat treatment and structural condition of aluminum alloy on the AE parameters.

Copper alloys with high strength and high conductivity are a serial of materials with excellent comprehensive performance. However, the strength and the conductivity are a pair of conflicting factors. To resolve this contradiction, Cu-1.0Cr-0.12Zr alloy was studied in this paper. With optical microscope, scanning electron microscope, Brinell hardness and the arms bridge, effects of heat treatment on microstructure and properties of such alloys was studied,and we strived to find a heat treatment processing to achieve the best match between the conductivity and the strength of the alloy. This paper focused on the study of conductive properties of the alloy. The main factor infuencing the conductivity of the alloy was the content of the soluting elements. The higher the content,the lower the conductivity, and vice versa. The results showed that the best comprehensive properties were obtained after solid solution at 920°C and then aging at 450°C for 180 min.

As the development of new materials and high speed machining, cutting fluid becomes more and more important because of its functions of cooling, lubrication, corrosion protection and cleaning. The main purposes of cutting fluid are decreasing temperature, reducing friction, extending tool life and improving machining efficiency. In precision machining, high machined surface integrity is the most important. In this paper, a preliminary experimental study on effect of two different cutting fluids on milled surface quality of iron-base superalloy was taken. The surface morphology, roughness, micro hardness and residual stress of the machined surface were investigated. The results showed that the material properties and geometric characteristics of the machined surface were significantly affected by cutting fluid conditions. The effect of cutting fluid on machined surface quality and service performance will become an important research direction. This paper also suggests the main contents of the further research on effect of cutting fluids on machined surface.

The paper presents the results of experimental research on the wear mechanism of the tool-electrode as a result of machining metal materials by applying electric discharges in pulse. It examines several phenomena noticed on the tool - electrode surface, exactly, the oxide layer formation and the modification of the micro geometry of the tungsten tool electrode surface. The paper presents the experimental results on the behavior of the tool electrode made of stainless steel after the metal parts have been machined. It also presents the phases of mass transfer in the gap between electrodes.

This paper investigates the influence of natural pre-ageing time on T6 peak hardness of rheo-high pressure die cast (R-HPDC) 6xxx series aluminium alloys. Natural pre-ageing has a negative effect on the 6xxx series Al-Mg-Si alloys that contain higher quantities of Mg2Si (typically > 0.90%). However, a positive effect is observed in alloys with lower quantities of Mg2Si. The negative effect can be attributed to the clustering of solute atoms that form at room temperature because the precipitates which develop directly from clusters formed at room temperature are coarser than those developed in alloys artificially aged immediately after quenching. The opposite occurs in alloys where a positive effect of natural pre-ageing is found. The effects of the duration of natural pre-ageing on the subsequent T6 properties are of importance. In this study the T6 (190oC-4h) hardness values of various R-HPDC 6xxx series alloys were determined after natural pre-ageing times ranging from 0h to 3240 hours. Alloys that show either the positive or the negative effect of natural pre-ageing are used. This paper also compares the influence of natural pre-ageing time on Cu-containing and Cu-free alloys. The addition of copper to the 6xxx series aluminium alloys lessens the negative effect of natural pre-ageing in the higher strength alloys.

The researches in the cutting domain have as purpose the cutting process economic optimization. This paper studies the cutting tool wear at drilling of the stainless steel X20Cr13. The experimental data and their subsequent processing represent the original contribution of the authors to the estimation of polytropic exponents and to the assessment in terms of structure of the calculus relation of the cutting tool wear. The obtained relationship of the cutting tool wear on the tool putting surface at drilling of the steel X20Cr13 permits the determination of the wear on the putting surface, in the case of a couple: stainless steel X20Cr13-Rp5 high-speed spiral drill, depending on the work parameters and the cutting conditions. Putting the condition of wear limitation, from the obtained relation, the cutting speeds are exactly given. The paper also contains graphs for the variation of the tool wear with parameters of the cutting technology. The results can be taken into consideration in the educational studies and in the theoretical technical research. They can be implemented in the manufacturing activity.

Micro-machining of hard dies and molds for optical parts or precision instruments is required to extend die and mold life. This paper investigates the effect of cutting fluid on diamond tool life under micro V-groove turning of cobalt-free tungsten carbide. Zinc dialkyldithiophosphate fluid (ZnDTP) displayed excellent diamond tool wear resistance in previous experiments. The performance of this cutting fluid is compared to newly developed vegetable oil based cutting fluid with dispersed MoS2 nanotubes. This paper investigates nanopolycrystalline diamond (NPD) tool life with a rake angle of 0° and-30° under continuous micro V-groove turning (i.e. face turning), of cobalt-free tungsten carbide using the developed cutting fluids. Superior diamond tool edge wear resistance is observed when using the dispersed MoS2 nanotubes in vegetable oil and using a NPD tool with a-30° rake angle.

The aim of this paper is, improving the characteristic of Ventilation mill for grinding coal which is one of the main part of steam power plants in the system that makes a significant influence on the level of energy efficiency with its work. Working parts of the mil during exploitation are dominantly exposed to intensive abrasive and erosive wear and also to impact loading at elevated temperatures, which can lead to damage and fracture of homogeneous materials, thus shortening their working life. For solving the problem of increasing the wear resistance of the parts for transport and coal grinding in power plants, to investigate the optimum application of technology in hard coatings by different procedures, and filer materials. Hard coatings were carried out with cold (plasma and arc treatment) and hot metallization (with concurrent and subsequent drowning). It has been used the additional materials of different chemical composition and properties based on Ni (NiCrBSi; NiCrBSiFe; NiCrBSi / WC) and Fe (FeCrCSiMo; FeCrCBSiTi; FeCrCBNiSi). The main goal of this paper is to make the selection of optimum hardfacing procedures, group of filler materials and hardfacing technology definition based on the results of structural and mechanical properties of samples, experimental model hardfacing. These were investigation of its structure, measurement and distribution of hardness in the samples, tribology characteristic samples with hard coatings. Based on the results of these tests there were selected the additional materials and procedures for applying hard coatings, which would be apply in the revitalization of parts in transport at and coal grinding.

The composite extrusion process, which is investigated at the Institute of Forming Technology and Lightweight Construction (IUL), allows the combination of different materials within an aluminum profile. In contrast to the useage of reinforcing elements, this paper focuses on the embedding of functional elements, such as isolated electric conductors. Results of the experimental and numerical investigations are presented within this paper.

In this paper research elements regarding the effect of water pressure variation on cut surfaces quality are presented in the field of abrasive water jet cutting of materials hard to process by machining such as austenitic stainless steels, in this case with a thickness of 20 mm. Selection of the optimal cutting process based on technical and economic criteria takes into consideration the type and thickness of the targeted material and also the physical and geometrical quality requirements. The present paper contains experimental research results regarding abrasive water jet cutting of austenitic stainless steel EN 1.4306 (ASTM 304 L) at different values of water pressure. The abrasive material used is Garnet with particle granulation 80 Mesh. By making roughness measurements and hardness examinations of the cut surface an evaluation will be made of the surface quality defining the optimal pressure values.

The authors developed “Dynamic Friction Polishing (DF polishing) Method” utilizing a thermochemical reaction between a diamond workpiece and a metal. This method enables high efficiency abrasive-free polishing of single crystal and polycrystalline diamonds (PCD) by simply pressing them against a stainless steel (SUS304) disc rotating at a high peripheral speed (VS>2500m/min). In the authors’ previous paper, a top of the diamond test piece (0.6mm×0.6mm, (100) plane) was removed at a rate of 2.6mm/min (0.94mm3/min) under the polishing condition of sliding speed VS=4000m/min, loading pressure P=130MPa and polishing time t=10s. A bottleneck for practical use of this method is a high pressure over 100MPa required for pressing a diamond workpiece against a rotating stainless steel disc. In this paper, a high efficiency tool was manufactured by electro-spark deposition of highly reactive special metals on a base disc tool. Among various reactive metals Nb and W brought very high efficiency in the polishing of a single crystal diamond.