Structural and Mechanical Properties of Silicon Carbide Mixtures Based on Boroethyl Silicate Binders

The rheologic properties of silicon carbide plastic mixtures with varying contents, in both concentration and type, of molding binders are analyzed. Ranges of binder concentrations, optimum for semi-dry pressing technology, are specified.     

Effect of the physicochemical properties of the components of temporary technological binders on the deformation behavior of corundum plastic mixtures

The physicochemical parameters of water-soluble polymers of different nature and the deformation properties of plastic corundum mixtures plasticized by their solutions with the concentration of the dispersion media close to the optimum molding concentrations were determined. It is recommended to design compositions of temporary technological binders and control the properties of plastic molding mixtures with allowance for the components of the temporary technological binder.Translated from Steklo i Keramika, No. 7, pp. 17–20, July, 1996.     

Effect of the boundary-layer parameters on technological properties of various oxide mixtures and semiproducts obtained by plastic molding

The effect of the composition of temporary technological binders (TTB) based on polyelectrolytes on the properties of plastic mixtures and air-dried semiproducts is considered. The TTB are rigid-chain polyacrylic acid and flexible-chain polybutylmethacrylate, nonionogenic methylcellulose, and polyvinyl alcohol, including those modified by aqueous dispersions (latexes). The parameters of the extent of the boundary layer and the coefficient of its compression are shown to be effective criteria for choosing TTB     

Properties of magnesite ramming mixtures for electric steel furnace bottoms

Conclusions Dead burned magnesite without free lime and with an alcohol sulfite binder is recommended for the production of carbon free ramming mixtures.Magnesite mixtures with the above binder retain high refractoriness and are sufficiently resistant to the effects of hydration in drying and firing rammed bottoms. In regard to firing properties they are superior to mixtures with fusible binders.Thoroughly rammed mixtures with a sufficient amount of fines produce a highly resistant bottom in electric steel-melting furnaces. A gradual sintering of the rammed mixtures occurs under the action of the migration of liquid metals at high temperatures in service.It is, therefore, recommended to base the production of magnesite ramming mixtures for electric steelmelting furnaces on dead burned magnesite with an alcohol sulfite binder.The use of the above mixtures in the industry would facilitate ramming and repair work in comparison to mixtures to which carbon binders have been added.     

Chemical factors that influence the performance of mine sulphidic paste backfill

Sulphide-rich tailings from four Canadian mines were sampled (Mines A1, A2, B and C) to prepare several different paste backfill mixtures. The sulphur grade within these tailings samples range from 5 to 32 wt.%. The binders used were Portland-cement-based binders, fly-ash-based binders and slag-based binders with proportions ranging from 3 to 6 wt.%. The study was carried out in two stages. Stage I allowed us to understand the effects of binder type, binder proportion and tailings properties on compressive strength development of paste backfill during the course of curing time. It was pointed out that for high sulphide tailings, neither the slag-based binders nor the fly-ash-based binders were effective, whereas the sulphate-resistant-based binder (mix of Type I [TI] and Type V [TV] Portland cements) gave good long-term strength. However, the slag-based binders gave the best strength for low and medium sulphide-bearing tailings for which the Portland- and the fly-ash-based mixtures have a relatively low strength. Stage II allowed us to study the early stage strength acquisition of the various mixtures. It was found that the chemical composition of the mixing water plays a role on the mechanical behavior of certain cemented backfills.     

Combustion mechanism of mixtures of binders capable of self-sustained combustion with inert and active fillers

A single mechanism for the combustion of mixtures of binders capable of self-sustained combustion with inert or active fillers is proposed. A mathematical model for the combustion of such mixtures is developed which takes into account the curvature of the burning surface of binder layers and the associated change in its burning rate. Parametric studies of the model are performed, and the calculation results are compared with experimental data on the combustion of mixtures of active binders with SiO₂, HMX, AP, and CL-20. It is shown that the proposed combustion mechanism and the developed model allow a unified explanation of all available experimental data for the class of compounds considered.     

Effect of Different Polymeric Matrices on Some Properties of Plastic Bonded Explosives

Matrices based on polyisobutylene (PIB), polymethyl‐methacrylate (PA), Viton A 200, Dyneon FT 2481 (Fluorel), and polydimethyl‐siloxane binders were studied as desensitizers. A series of plastic explosives (PBXs) were prepared, based on four different nitramines, namely RDX (1,3,5‐trinitro‐1,3,5‐triazinane), β‐HMX (β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane), BCHMX (cis‐1,3,4,6‐tetranitro‐octahydroimidazo‐[4,5‐d]imidazole) and ε‐HNIW (ε‐2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane, ε‐CL‐20), bonded by the matrices mentioned. For comparison, pentaerythritol tetranitrate and certain commercial explosives based on it, Semtex 1A, Semtex 10 and Sprängdeg m/46, were used. Detonation velocities, sensitivities to impact and friction, and peak temperatures of thermal decomposition by differential thermal analysis technique (DTA) for all the explosives studied were determined. Heat of detonation was calculated by means of a thermodynamic calculation program (EXPLO 5 code). Fluoroelastomers have a neutral to positive effect on the thermal stability of nitramines and they have a significant effect on decreasing the friction sensitivity. However, their anti‐impact efficiency is the lowest in this study although they have a positive effect on performance of the corresponding PBXs. PA and PIB matrices markedly decrease thermal stability of nitramines, the anti‐impact influences of PIB‐binders are better than those of PA‐binders, while PA‐binders have a higher anti‐friction effect and slightly less negative influence on the performance of the PBXs in comparison with PIB mixtures. The polydimethyl‐siloxane matrix has a neutral effect on thermal stability of the nitramines studied, it has an influence on the volume thermochemistry of detonation comparable with that of fluoroelastomers although it does not provide comparable performance, and its corresponding PBXs have optimum sensitivity parameters.     

A new direction in the creation of ceramic materials with a specified composition and structure. Part 1. Manufacturing binders for the ceramic industry by the solgel method. 5. Preparation and physicochemical properties of ethylsilicate binders for ceramic and refractory production

Compositions and methods for preparing various ethylsilicate binders for the production of ceramics and refractories are presented. The physicochemical features of the transformations of the created binders recommended for cast and pressed articles, unshaped mixtures, and coats and adhesives are considered. It is shown that for each filler and design of the material the binder should be chosen so as to provide the specified phase composition and structure 1The previous papers of the series have been published in Nos. 1–3, 5, and 7, 1999.     

塑料涂料的研究现状与展望

从塑料涂料的成膜基料、涂料性能、施工应用等方面,阐述了国内外塑料涂料的研究现状,并提出了塑料涂料研究存在的问题与发展要求.     

Modeling of mold filling process for powder injection molding

The mold filling process has been modeled for the injection molding of different polymer-based binders and powder-polymer mixtures. It is essentially a two dimensional non-Newtonian fluid flow analysis in a non-isothermal environment. A complete analysis is accomplished by combining a finite element method and control volume technique to describe an increment of flow front movement, whereas a finite difference method is used to solve the energy equation to characterize the temperature distribution. Numerical results are compared to exact solutions for a circular ring cavity using a power law fluid model under an isothermal condition. Comparison of computed results against published data for a simple circular disk shows good agreement between the two analysis methods. After making selected comparison studies, it is demonstrated that the filling process in Powder Injection Modeling with different combination of powder-polymer mixtures is markedly dependent on specific combinations of powder; and polymer based binders. Computed flow front results for a rectangular cavity also compared favorably against the data for a power law fluid model under non-isothermal conditions.     

硝基快干汽车修补漆的制备

通过试验,用1/2s硝酸纤维素溶液和热塑性丙烯酸树脂制备硝基快干汽车修补漆,讨论了二者比例、氨基树脂、增塑剂和有机溶剂等对涂料性能的影响。结果表明,当1/2s硝酸纤维素溶液和热塑性丙烯酸树脂比例为38∶39,丁基化三聚氰胺甲醛树脂添加量为4.5%,邻苯二甲酸二丁酯添加量为3%,有机溶剂选择恰当时,该硝基涂料的综合性能良好。     

Bioactivity of antifouling paints based on organotin toxicants

This paper discusses the bioactivity of antifouling paints based on organotin toxicants, such as tributyltin fluoride (TBTF) and triphenyltin fluoride (TPTF). These compounds were used alone or mixed as the main toxicant in formulations. The use of TPTF or mixtures of TPTF and TBTF, with vinyl binders, led to paints with satisfactory bioactivity during a 24 months immersion period. With the same binders, TBTF alone provided only 12 months of antifouling protection. The correlation coefficients calculated from the fouling attachment values and the rosin content in the binder showed that the bioactivity of the tested formulations depended on the solubility of the toxicant in sea water and on the composition and solubility of the binders.     

单组分塑钢门窗专用涂料的开发

通过选用合适基料、溶剂、颜料等制备了塑钢门窗专用涂料,并讨论了影响漆膜性能的各种因素。     

Investigation of Antiadhesion Coatings for the Sag Bending of Silicate Glass

In the article, the features of the interaction of different forms of carbon with various solvents are investigated comprehensively, and the nature of defects and their effect on the optical and physicochemical properties of coatings are studied. The compositions of high-temperature antiadhesion parting mixtures for sag bending which are based on the high-temperature lubricants of carbon-containing materials are investigated. Base on the research, the mechanisms of the coagulation of particles during heat treatment, the effect of the structure and particle size of the studied mixtures on the coating quality, and the interaction with binders were studied, which made it possible to obtain high-temperature antiadhesion coatings with predetermined characteristics. The technology of applying these mixtures on the surface of glass billets and removing them from the glass surface, while meeting the environmental safety requirements, is developed.     

Heat-resistant thermally insulating concretes with phosphate and aluminate binders

This article describes heat-resistant thermally insulating concrete mixtures and products with phosphate and aluminate binders, their properties, and the main processes used to make them. The thermophysical properties required of thermal insulation are obtained together with an increase in its strength thanks to the production of denser but less heat-conducting concretes with fillers composed of aluminum microspheres.     

STUDY OF SEVERAL GROUPS OF ORGANIC BINDERS UNDER LOW-PRESSURE EXTRUSION*

A number of organic binders were added to a talc-water system and the mixtures were extruded at low pressures through a deairing extruder. These binders were (1) flours, starches (both short and long chain), (2) gums, (3) alcohols and cellulose derivatives, (4) wood extracts, and (5) alginates. Data are presented on wet strength, water retention during extrusion, extrusion characteristics, drying shrinkage, water of plasticity, days required to air dry, warpage, dry modulus of rupture, hardness, and migration.     

The influence of cohesion and adhesion parameters on the fatigue life of hot mix asphalt

Fatigue cracking is one of the major distresses of hot mix asphalt (HMA) at moderate temperatures. Two of the main properties of asphalt mixtures affecting fatigue are the cohesive bond energy of asphalt binder and the adhesive bond energy between asphalt binder and aggregate. These two parameters were calculated using surface free energy (SFE) theory. Furthermore, the fatigue life of asphalt mixtures was measured by indirect tensile fatigue test. The results showed that asphalt mixtures with limestone aggregates, with the most specific surface area, and magnitude of adhesion had the highest fatigue life. Moreover, asphalt mixtures made with asphalt binder having the highest penetration had greater fatigue life than the other mixtures. The enhanced fatigue life was attributed to the greater cohesion energy and higher resistance to fatigue cracking in asphalt film. Also, these mixtures had the highest adhesion energy on the contact surface between asphalt binders and aggregates, which increased the energy required to separate the asphalt binder from the aggregate surface and the occurrence of adhesion rupture distress.     

Effect of processing variables on the linear viscoelastic properties of SBS‐oil blends

Block copolymers, especially styrene‐butadiene‐styrene three‐block copolymers (SBS), are recognized as especially effective asphalt modifiers because of their thermoplastic elastomeric properties. The concentration of copolymer, its ability to swell by the maltenic oils, and the processing variables are essential in the development of a three‐dimensional network in the polymer‐rich phase that enhances the vis‐coelastic properties of these modified binders. This swollen polymer phase may influence the mechanical properties of the modified bitumens and synthetic binders. This paper deals with the influences that processing variables exert on the linear viscoelastic properties of oil/SBS mixtures in a wide range of temperatures. From the experimental results obtained we may conclude that most of the oil/SBS blends studied are highly structured thermoplastic gels above a critical SBS concentration that depends upon temperature, time of processing and surrounding atmosphere.     

Refractory concretes of a new generation. Rheological aspect of their technology

The distinctive features of the rheological behavior of bonding systems and concrete mixtures are generalized and analyzed as applied to the technology of ceramoconcretes, low-cement refractory concretes, and liquid vibrocompacted thixotropic refractory mixtures. The foundations of the principle of rheotechnological correspondence in the technology of refractory concretes are formulated. An important role of vibrations for controlling the rheological properties (vibrorheology) is demonstrated. The principal factors decisive for the rheological properties of binders and concrete mixtures are analyzed. The important role of the temperature factor is considered and the problem of development of a “warm” technology of refractory concretes is posed. The processes of mixing in the technology of refractory concretes are also discussed. Translated from Ogneupory, No. 4, pp. 6 – 15, April, 1994.     

Extrusion Molding of Sorbents Based on Synthesized Zeolite

The possibility of producing complex-profile thin-walled sorbents based on synthesized zeolite is investigated. It is proposed to use natural aluminosilicate as binders. Methods have been developed for controlling properties of zeolite-based molding mixtures by introducing a plasticizer or by alkali or acid modifying the binder structure.