Research of the influence of highcarbon steel wire drawing speed on stresses and deformations on wire cross section

The parameters of wire production affecting the distribution of residual stresses and strains on the wire cross section are considered. It is determined that the modes of coarse drawing can affect the complex of mechanical properties of thin wire due to the uneven distribution of equivalent stresses and strains. The rough drawing speed is chosen as the investigated parameter.The effect of the coarse drawing rate of high-carbon steel wire on the distribution of equivalent residual stresses and strains over the wire cross section is studied by numerical simulation of wire drawing at different speeds by the finite element method. The values of equivalent residual stresses for the selected drawing route along the wire cross-section zones are determined. The analysis of the equivalent stress distribution over the wire cross section is made.It is shown that the increase in the speed of coarse drawing increases the uniformity of the distribution of equivalent residual stresses, does not have a negative effect on the deformed state of the wire, increases the absolute values of equivalent residual stresses, slightly reduces the absolute values of residual deformations.

Modification of the titanium implants surface with TiO2 coatings obtained by sol-gel method via dip-coating

Within the framework of the study, TiO2 coatings were obtained by sol-gel method via dip-coating. For the films obtaining, manual drawing the substrate from the solution at a relatively high rate of 30 mm / min and automated drawing from the solution at low drawing rates (from 1 to 10 mm / min) were used. The morphology of coatings has been studied by scanning electron microscopy. The influence of the mode and the rate of drawing of the substrate from the solution on the films morphology was demonstrated. Analysis of the data showed, that the surface morphology of the coatings obtained at lower drawing rates by an automated method is much more homogeneous - the titanium dioxide films completely repeats the topography of the substrate surface, there are practically no fissures. Qualitative coatings of titanium dioxide, completely replicating the surface relief of the substrate, can be obtained by this method. Selection of the substrate drawing rate allows reducing the influence of the substrate topography and avoiding the appearance of crystallization centers, and as a consequence, the appearance of defects in the morphology of coatings, such as fissures or microparticles.

Precipitation in Surface Zone of Continuously-Cast Slab of ULC/IF Steel Microalloyed with Titanium

The aim of this work was to analyze the morphology and distribution of the microalloy precipitates in the slab surface zone of ULC/IF steel microalloyed with titanium. The slab was made by continuous casting using two different slab pulling rates. Transient slabs were pulled with pulling rate 0.4 m/min at the start and 0.8 m/min at the end of the slab. It was confirmed that morphology of the particles evaluated in the surface areas of slab were globular, cubical or elliptical shape and have been identified as of TiS, TiN and TiC. At the lower drawing rate particles from the middle cut-out from an area with coarse ferritic grains at the slab surface attained an mean size of 2r = 41.8 nm, and from an area with fine ferritic grains they attained an mean size of 2r = 32.5 nm. At the higher drawing rate particles in the middle cut-out attained an mean size of 2r= 63.5 nm. The coarser particles were found in areas with coarse ferrite grains and at higher pulling speed.

Study on Improvement of Simulation Model of Fully Mechanized Top-Coal Caving

Based on the traditional David Jolley nine body stochastic simulation model, this article has designed a number of simulation programs of different drawing interval and refuse content. Research indicates that of top coal drawing body in this model upper width compared to lower width is small 1.3 ~ 1.7m, with the top coal drawing rate 50~71%. Improve the traditional stochastic simulation model of fully mechanized top-coal caving, considering temporary retention problems in top vacancy diffusion and horizontal fill issues in module. Under the same working face condition, it additionally builds the improvement simulation programs of different horizontal fill probability. Research shows that 10% increase in horizontal probability, the top coal drawing amount increases 2.2%. When horizontal fill probability reaches 30 to 40%, the top coal drawing ellipsoid body grows to be perfect.

Synthesis, modification, and characterization of organosilicone and acrylate copolymer latex

Silicone elastomers are well known for their interesting physical and chemical properties such as low surface tension and surface energy, high energy of Si–O bond, good molecule flexibility, increased modulus, decreased thermal expansion coefficient, increased heat distortion temperature, reduced gas permeability, better fire-retardant properties, enhanced ionic conductivity, low flammability, increased solvent resistance, lower material cost, and ease of preparation and processing. High-silicon-content silicone-acrylate copolymerization emulsion by octamethylcyclotetrasiloxane (D4) and acrylic ester was synthesized and characterized in this article. About 20 wt% silicon content gave the latex film a rubberlike characteristic as shown by the study of the resilience and tensile curve of the silicone-acrylic latex film. The emulsions were characterized using Fourier transform infrared spectroscopy. A Mastersizer 2000 particle size distributor from Malvern Instruments was used to measure the particle size distribution of the organosilicone-acrylate copolymer emulsion. In this article, the thermal properties of the copolymers were studied using thermogravimetric analysis. The morphology structure of the latex film was determined by transmission electron microscopy. The analysis results indicated that the latex film presented high drawing rate and high elasticity. Compared with common polymer fluid, the latex displayed a sound performance in flowability, elastic resilience, and industry application value.

Theoretical model for the hot-melt-drawn fabrication of optical fibre probes and analysis of fabrication parameters

Optical fibre probes made by manually operated hot-melt-drawn methods may have unreliable production quality. This can result in unreliable results during use of the probes. This article presents a theoretical model for the construction of optical fibre probes by a hot-melt-drawn method, intending to simulate the optical fibre melt-drawing process using the P-2000 Sutter melt-drawing installation, and investigates changes in length, radius, and geometric profile of the optical fibre. Using preset processing parameters, the study simulates the profile, size, and shape of an optical fibre probe, and the geometric shape and diameter of the probe tip. Additionally, the article presents an analysis of fabrication parameters to determine which of the three processing parameters, probe diameter, melt-drawing rate, and hard-drawn value, is most significant in determining the length and profile of a simulation model probe.

Direct-Write Fabrication of Polymer Nanocomposite Fibers

ABSTRACTThe unique properties of carbon-nanotube (CNT)-doped polymers have generated several promising applications including gas sensors, high-strength/light-weight materials, and electromagnetic interference shielding. The ability to process CNT-doped materials into complex architectures may enable further advancement of these devices. We have developed a direct-write technique for processing CNT-doped poly(methyl methacrylate) (PMMA) into 3D arrays of precisely-positioned fibers with micro- and sub-microscale diameters. In this method, a programmable micromanipulator-controlled syringe was loaded with solvated CNT/PMMA and utilized to draw an array of freely-suspended solution filaments on a substrate in a “connect-the-dots” fashion. As the filaments are drawn, they are thinned by surface tension-driven necking as they dry and form solid fibers. The degree of thinning can be controlled by varying the viscosity of the solution, which acts to resist the necking while the volatile solvent evaporates and solidification occurs. Multiple fibers were drawn to investigate the effects of several factors on fiber diameter and process yield. These variables included fiber length (4, 8, and 18 mm), fiber drawing velocity (5 and 20 mm/s), polymer concentration in solution (22 and 24% by wt.), and CNT concentration in solution (0, 0.5, 1, and 1.5% by wt.), with the latter two of these variables strongly influencing solution viscosity. Measurement of the fibers via scanning electron microscopy (SEM) revealed several trends: Fiber diameter was not influenced by CNT concentration, but increased with increasing PMMA concentration (P<0.001), increasing drawing rate (P<0.01), and decreasing fiber length (P<0.001), with fiber diameter ranging from 538 nm to >100 μm. Furthermore, fiber yield exceeded 75% for all tested solutions except for the lowest viscosity CNT-doped solution (24% PMMA/0.5% CNT, η=50.1 Pa*s), which experienced capillary breakup prior to solidification. The conductivities of direct-write PMMA/CNT fibers ranged from <10-7to 0.15 S/m, with shorter fibers having higher conductivities (P<10.005). Also, fibers drawn from solutions with 1.0% CNTs had higher conductivities that those drawn from solutions with 0.5% or 1.5% CNTs (P<0.01). This nonlinear trend was further investigated by cleaving fibers in liquid nitrogen and imaging their cross-sections with an SEM. This analysis illustrated that the CNTs, which were functionalized to remain dispersed in the solvent, tended to randomly aggregate within the polymer-fiber matrix, particularly for fibers drawn from solutions containing 1.5% CNTs. In conclusion, CNT/PMMA fibers were successfully drawn with the direct-write technique and CNT doping had no significant influence on fiber diameter or yield compared with fibers drawn from PMMA homopolymer. However, the CNTs were found to strongly aggregate when drawn from solutions loaded at high concentrations (1.5%), thereby hindering electrical transport.

Optimisation of Hollow Glass Fibres and their Composites

Hollow glass fibre reinforced plastics have a structural performance niche in a class of their own. They offer increased flexural rigidity compared to solid glass fibre reinforced plastics, they offset the need for thin sandwich construction which is both difficult and expensive, and they provide an opportunity to develop laminates with improved or tailored characteristics. An experimental hollow glass fibre manufacturing facility is in operation at the University of Bristol. The facility is capable of drawing precision hollow glass fibres of various diameters with varying degrees of hollowness under precise parameter control. Hollow borosilicate glass fibres have been manufactured from tubular preforms with a variety of internal and external diameters, which correspond to a range of hollowness values. In all cases, the resulting hollowness was reduced from that present in the preform state, regardless of drawing rate or furnace temperature. In fact, temperature has been demonstrated to be of paramount importance in controlling fibre hollowness due to the interaction between glass viscosity and surface tension effects. These results suggest that for a given temperature and draw rate there is a single condition where fibre hollowness is maximised and external diameter minimised.