Semi-industrial Conditions Research Articles

Tribological behaviour of W–Ti–N coatings in semi-industrial strip-drawing tests

W–Ti–N sputtered coatings were tested in semi-industrial conditions by strip drawing to access their ability for sheet metal forming. Both laboratory and industrially developed coatings were tested. In a first part of the study the upscale of the deposition of the W–Ti–N coatings was achieved. The main difference between the two types of coatings was the evolution of the chemical composition with the N content. However, similar trends in the hardness and scratch-test results were encountered being the best compromise of these properties reached for ∼40 at.% N in the industrially deposited films against the 35 at.% N for laboratory deposited ones. Excellent results were found in the strip-drawing tests for coated samples in comparison with uncoated tools. In any of the conditions tested no adhesion between the tool and the sheet material was found when 1 g m −2 of lubricant was used. Similar results were found between laboratory and industrially deposited coatings.

Status and prospects for production of carbon fibres based on polyacrylonitrile

Production of PAN-based carbon fibres (CF) is a rapidly developing sector. Production in 2006 was 28,000 tons. The production capacities in 2007 increased to 55,500 tons and will attain 66,000 tons in 2008. The Japanese companies Toray, Toho, and Mitsubishi are the leaders and are responsible for 77% of total production. Toray is the leader with respect to fibre quality. The CF manufactured by the company basically have a strength of 500–560 kgf/mm2. The properties of the PAN precursor are of decisive importance for the quality of the CF. Each company has its own PAN precursor plant for successfully competing. The fibre manufactured in the RF has a strength of 300–350 kgf/mm2. Uglekhimvolokno NlTs has developed technology for production of CF with a strength of 450 kgf/mm2. Economy in production of CF is attained by creating units (flow production lines) with individual capacity of 150–200 and even 400 tons/year (the capacity of existing domestic units is 10–20 tons/year). This increase in capacity is attained by using primarily new technical solutions, including conductive tempering of oxidized tows, separate air-oxidant and air-heat carrier circulation, making the PAN tow compact by selecting an appropriate oiling agent, and vertically positioning the carbonization furnace stack. The maximum modulus of elasticity of PAN CF is 60,000 kgf/mm2. To attain high orientation and a high degree of crystallinity, boron, which decreases the temperature of transition of the fibre into the highly elastic state and thus facilitates the occurrence of orientation drawing and crystallite growth, should be used as a plasticizer. In semi-industrial conditions, when boron is added in the stage of oxidation in the form of boric acid, CF with a modulus of elasticity of 47,700 kgf/mm2 are obtained. To prolong the lifetime of the graphite heaters, it is recommended that they be given a shape that allows focusing radiation on the processed fibre. Thin carbon fillers in the form of prepregs 0.04–0.17 mm thick and fabrics 0.11–0.15 mm thick are manufactured to increase the uniformity of the properties of multilayer composites. Prepregs made of “thick” PAN tow with a linear density of 3.2 ktex which are processed into CF with a strength of 500 kgf/mm2, elongation of 2%, and modulus of elasticity of 23,000 kgf/mm2, are the most economical. In the RF, unidirectional slivers of the Elur type 0.08 mm thick are manufactured for these purposes, but they have lower strength and due to the low processing speeds, high cost. These drawbacks have been eliminated in the semicontinuous method for manufacturing thin PAN fibres.

Enhancement of marennine production by blue light in the diatom Haslea ostrearia

The marine diatom Haslea ostrearia Simonsen produces a blue pigment, marennine, which is used for greening oysters. This microalga is cultured industrially indoors with artificial light. The influence of light quality on marennine production by cultures of H. ostrearia was investigated in the laboratory and at a semi-pilot scale (300 L tanks). In the first series of experiments in the laboratory, a clone of H. ostrearia was cultured under light of different colors (white, blue, green, yellow, and red) and at two irradiances (‘low’ and ‘high’, 20 and 100 μmol photons m−2 s−1, respectively). Compared to the white light controls, growth was increased in blue light at the ‘low’, but not at the ‘high’ irradiance, and marennine production at the end of the exponential phase was the highest in cells grown under blue light, regardless of the light quality or intensity during growth. Increased marennine production during growth was also observed, whichever color of light (blue or white) was used during the acclimation phase. In a second series of experiments, intraclonal differences were studied by comparing marennine production in seven clones differing with regard to their mean cell size. The total marennine expressed either per cell or per culture volume, was higher in blue light for all the clones. Complementary experiments carried out under semi-industrial conditions confirmed this effect of blue light, which could be relevant for the industrial, indoor production of marennine.

Investigation of microstructure prediction during experimental thermo-mechanical plate rolling

In this study results of experimental and theoretical research of modeling of microstructure in hot rolling process of steel carbon plates with niobium are presented. Models describing kinetics of recrystallization of a deformed austenite and precipitation of niobium carbon-nitrides were verified in semi-industrial conditions. The main aim of the experimental study made in present paper were determination of distributions of microstructure parameters after partly steps of thermo-mechanical steel rolling.

Olivines of the Kola Peninsula. II. Magnetic Concentration of Olivinites

A patented technology for dry magnetic concentration of olivinites developed and tested in semi-industrial conditions for the production of high-quality olivine concentrates is described. Concentration of olivinites of the Khabozerskoe deposit rich with sungulite yields an additional sungulite product.

The “Reactor STM”: A scanning tunneling microscope for investigation of catalytic surfaces at semi-industrial reaction conditions

An instrument is introduced that combines a scanning tunneling microscope (STM) and a small volume (300 μl) flow reactor, for the in situ study of catalytic surfaces at semi-industrial conditions. The tip is led through a gold membrane separating the reactor from the rest of the STM. We show (1) that the scanning through the membrane is possible with no noticeable effect of the membrane; (2) that it is possible to image surfaces in a gas flow of 10 ml/min, and that the imaging is unaffected by moderate changes in the flow conditions during the scanning; and (3) that imaging of atomic steps is possible on a Co(0001) surface in a reactive environment at room temperature and at elevated temperatures. Furthermore, it is observed, that the step mobility on Co(0001) is strongly enhanced in the presence of H2.

The analysis of microstructure change during Multi-Pass rolling of a steel with niobium

The present paper describes experimental and qumerical analyses for prediction of microstructure changes during hot plate rolling, which was conducted in Metal Forming Department Czestochowa, Technical University. Models describing kinetics of recrystallization of deformed austenite and precipitation of niobium carbon-nitrides were evaluated in semi-industrial conditions. The main objective of simulation using finite element methods was to determine temperature and strain distributions in the roll gap and parameters of mi crostructure through thickness of rolled plates. The experimental results were compared with computer simulation results, which showed thai: retained strains accumulated during the previous passes have a big influence on stability of distribution of mechanical properties.

Study of carbonaceous deposits on fischer-tropsch oxide-supported iron catalysts

Fischer-Tropsch synthesis was performed at semi-industrial conditions (300°C, 1515 kPa, H 2/CO = 1) on various oxide (SiO 2, A1203, TiO 2, ZrO 2)-supported iron catalysts. The carbonaceous materials deposited on the catalysts after 260 h on stream were characterized by FTIR spectroscopy and thermogravimetry during temperature-programmed oxidation, and by 57Fe Mossbauer spectroscopy. The characteristics of the carbonaceous deposits were strongly affected by the nature of the catalyst supports. At least five different forms of carbonaceous materials have been identified: aliphatic, aromatic, oxygenated, carbidic, and amorphous. Iron carbides have been found in all used catalysts. Mössbauer spectra of all used catalysts after heating in air at 400°C showed reoxidation of all carbides to α-Fe 2A 3. A tentative correlation of the carbonaceous deposit characteristics with the nature of the catalyst supports is offered.

Firing Savinsk magnesite in rotary kilns

Savinsk magnesite (lump and briquetted from the concentrate) can be thoroughly fired in rotary kilns of different sizes at a flame temperature of 1700–1750°C. The porosity of the powder is proportional to the size of the charge of raw material. During the firing of lump magnesite of all grades and briquette from ground concentrate it is possible to obtain powder with a porosity of 5–7%. When magnesite is being fired in a rotary kiln with a preparatory grid and when the raw materials charged amount to 1.5–2.0 times greater than when firing is done without the grid, a moderate-porosity powder is obtained. Thus, the fitting of a preparatory grid may increase the output of the furnace, and improve the quality of the product. During the firing of Savinsk lump and briquetted magnesite in rotary kilns in semiindustrial and industrial conditions, there is no bear formation, ringing, or crust formation on the lining of the furnace.

Investigation of the processes used in producing electrical contact cermet materials

1. From the contact materials produced, tungsten-silver compositions proved to be the best with respect to density and wear resistance under the operating conditions. On the other hand, tungsten-copper contacts displayed great hardness and a very great density at high pressures. It is necessary to continue the production of contacts for medium-duty and semiindustrial conditions. 2. Sintering by means of high-frequency heating is a good method for producing contacts based on pure tungsten. The results obtained, although they are not final, have been satisfactory so far. 3. The construction of a device for testing contacts for electroerosion will make it possible to gather new experimental data, compare the materials produced with the imported ones, and to select materials with the optimum properties.