PL226615B1 - Ceramic mass of expansion properties - Google Patents

Description

Description of the invention

The subject of the invention is a ceramic slurry with expansion properties (shear thickened).

Shear thickening fluids are a group of non-Newtonian fluids characterized by an increase in viscosity with increasing shear rate or applied shear stress. Such materials, with properties known as dilatants, belong to the group of intelligent materials, i.e. they change their properties, in this case rheological, in a predictable and reversible manner under the influence of external factors. Under the influence of impact, the expansion material changes from the properties typical of liquids to those of a solid. Due to the unique property of these liquids to absorb and dissipate energy, research is currently being carried out on the use of this type of fluid, e.g. for impregnating fabrics from which protective clothing can be produced, e.g. in the military [Wetzel ED, Lee YS, Egres RG, Kirkwood KM, Kirkwood JE, Wagner NJ, The Effect of Rheological Parameters on the Ballistic Properties of Shear Thickening Fluid (STF ) - Kevlar Composites. NUMIFORM, 2004; Lee Y., Wetzel E., Egres Jr R., Wagner N., Advanced Body Armor Utilizing Shear Thickening Fluids Army Research Laboratory Aberdeen Proving Ground, 2009], or protective gear for athletes. Fluids with such properties may also find application in the automotive industry in the production of silencers [Zhang X., Li W., Gong X., The rheology of shear thickening fluid (STF) and the dynamic performance of an STF-filled damper, Smart Materials and Structures, 2008, 17, 035027 -035034] and in the protection of buildings against seismic shocks. Preliminary studies have shown that materials based on shear-thickening fluids not only very well absorb impacts and shocks, but are also flexible and lighter than standard p-aramid materials used to protect the human body.

In the preparation of shear thickening systems, ceramic powders and organic dispersing liquids (most often polypropylene and polyethylene glycols) or water are used [Decker M. J.,

Halbach C. J., Nama C. H, Wagner N. J., Wetzel E. D., Stab resistance of shear thickening fluid (STF) -treated fabrics, Composites Science and Technology, 2007, 67, 565-578; Hoffman R. L., Discontinuous and Dilatant Viscosity Behavior in Concentrated Suspensions, Observation of a Flow Instability, Transactions of the Society of Rheology, 1972, 16, 155-173; Kamibayashi M., Ogura H., Otsubo Y., Shear-thickening flow of nanoparticle suspensions flocculated by polymer bridging. Journal of Colloid and Interface Science, 2008, 321, 294-30]. In water systems, the powder settles quickly and easily forms hard deposits. When glycols are used, slurries that are quite stable over time are obtained. Among the ceramic powders in the scientific and patent literature, the most distinguished are nano- and micrometric silica [Wagner N.J., Dynamie properties of shear thickening colloidal suspensions, Rheological Acta 2003, 42, 199-208; Newstein MC, Wang H., Baisara NP, Lefebvre AA, Shnidman Y., Microstructural changes in a colloidal liquid in the shear thinning and shear thickening regimes, Journal of Chemical Physics 1999,111, 4827-4839], less often poly (methyl methacrylate ) (PMMA), calcium carbonate, titanium dioxide, AI2O3 and SiC compositions or kaolinite [Kalman DP, Schein JB, Houghton JM, Laufer CHN, Wetzel ED, Wagner NJ, Polymer dispersion based shear thickening fluid-fabrics for protective applications, Proceedings of SAMPE 2007, Baltimore, MD, 2007; Decker M. J., Halbach C. J., Nama C. H., Wagner N. J., Wetzel E. D., Stab resistance of shear thickening fluid (STF) -treated fabrics, Composites Science and Technology, 2007, 67, 565-578; M.D. Chadwick, J.W. Goodwin, B. Vincent, E.J. Lawson, P.D.A. Mills, Rheological behavior of titanium dioxide (uncoated anatase) in ethylene glycol, Colloids and Surfaces A: Physicochemical and Engineering Aspects 2002, 196, 235-245; Bergstrom L., Shear thinning and shear thickening of concentrated ceramic suspensions, Colloids and Surfaces A: Physicochemical and Engineering Aspects 1998, 133, 151-155; Rosen B. A., Nam Laufer C. H., Kalman D. P., Wetzel E. D., Wagner N. J., Multi-threat performance of kaolin-based shear thickening fluid (stf) -treated fabrics, Proceedings of SAMPE 2007, Baltimore, MD, 2007].

Among the SiO2 powders, the most attention is paid to the spray nanopowder, commercially known as silica fumed [Wu Q., Ruan J., Huang B., Zhou Z., Zou J., Rheological behavior of fumed silica suspension in polyethylene glycol, Journal of Central South University of Technology 2006, 13, 9784-1005; Yang H., Ruan J., Zou J., Rheological responses of fumed silica suspensions under steady and oscillatory shear, Science in China Series E: Technological Sciences 2009, 12, 845-860]. The main advantages of using silica fumed nanopowder are its availability,

Lightness and hardness. The problem is, however, a slight dilatation effect and significant instability of rheological parameters over time, resulting mainly from the uniform size and shape of the powder grain.

This problem was solved thanks to the use of halloysite in the slip - a mineral belonging to the group of aluminosilicates with the formula Al ₄ [Si ₄ O ₁₀ ] (OH) ₈ -10H ₂ O and with a unique morphology.

The ceramic mass with expansion properties according to the invention is a mixture of nanosilica and halloysite powder dispersed in a liquid organic compound, in which the proportion of halloysite is from 1 to 20% by volume. based on the volume of the solid phase, and the total solids concentration in the mass is from 10 to 30 vol.%.

Preferably, the stock comprises halloysite powder with an average grain size from 3 to 400 nm.

Preferably the mass comprises halloysite previously subjected to a magnetic separation process to separate magnetic fractions such as Fe2O3, Fe3O4, TiO2, amorphous iron hydroxides, magnetite, hematite and ilmenite.

Preferably the mass comprises halloysite prepared by mixing the powder with a mixture of C1-C3 alcohol with glycol and / or polyglycol, preferably in a weight ratio of 2: 1, followed by centrifugation for 10 to 40 minutes at a speed of 10000-13000 rpm. , drying and grinding.

Preferably the mass contains silica fumed nanosilica with a nominal average grain size from 3 to 400 nm.

Preferably, the mass contains nanosilica, which has been previously suspended in an organic solvent, and then subjected to a centrifugation and drying process.

As the liquid organic compound, glycol and / or polyglycol are preferably used, most preferably poly (propylene glycol). Preference is given to using polypropylene glycols with molecular weights of from 4OO to 8OO g / mol.

Halloysite is a widespread, common mineral. Some of the halloysite grains are in the form of nanotubes with a diameter of 30-5O nm and a length of up to several hundred nm, which makes this type of grain shape particularly interesting for applications with shear thickening liquids. This type of mineral has not hitherto been used to obtain shear thickening liquids. It turned out that the addition of halloysite to ceramic masses based on nanosilica has a positive effect on the mass properties. It also reduces the cost of its production. The ceramic mass according to the invention is characterized by stability and a significant, steep jump in viscosity. The use of halloysite in an appropriate amount, as an additive to ceramic masses based on nanosilica, increases the expansion joint. The lower the concentration of nanosilica, the higher the viscosity jump. By adding halloysite to the shear thickened suspensions, it is also possible to influence the speed of the jump. With the increase in the concentration of halloysite in the mixture, an increase in the value of the shear rate at which the expansion jump occurs is observed, thanks to which, by adding halloysite to expansion compounds based on nanosilica, it is possible to control the rheological characteristics of such slips.

It is preferable to pre-prepare the nanosilica by swirling the powder with ethanol and the dispersing liquid. The centrifugation process allows for the modification of its surface by removing the water adsorbed on the surface of the ceramic nanopowder, which then facilitates the wetting of this powder with an organic dispersing liquid. After centrifugation, the powder is dried in air or at elevated temperature. This allows to increase the dilatation effect, i.e. the viscosity jump at a specific shear rate, and also gives the possibility of introducing more solid phase.

One of the advantages of halloysite over nanosilica, apart from the lower price, is also its natural origin, which significantly increases the availability of this powder.

According to the invention, the use of glycols and / or polyglycols is preferred due to their neutral (non-toxic) effect on humans and the environment and their miscibility with water in any ratio.

The subject of the invention is presented in more detail in the embodiments.

P r z k ł a d 1.

In order to obtain the material thickened by shear, as a solid phase, synthetic silica Fumed (SF) and halloysite with average grain sizes of 14 nm and 300 nm, respectively, were used. The dispersant was poly (propylene glycol) with a molecular weight of 725 g / mol (PPG 725).

The solid phase accounted for 12% by volume. the whole mass. The volume ratio of nanosilica to halloysite in the solid phase was 97: 3 and 99: 1, respectively. The masses were mixed in a vessel placed in a thermostat4

Stirring at 54 ° C with a mechanical stirrer for 3 hours. The stirrer was rotated at a speed of about 100 rpm.

After the homogenization process, the ceramic slip masses were subjected to rheometric measurements on a plate-plate rheometer at a temperature of 25 ° C. The distance between the plates was 0.7 mm. -1

The set speed of the upper plate increased from 1 to 500 s ^-1 .

The obtained masses were characterized by the viscosity jump effect equal to 354 Pa-s (97: 3) and 316

-1 -1

Pa-s (99: 1) with a shear rate of 7.8 s ^-1 9.8 s ^{-1, respectively} .

P r z k ł a d 2.

In order to obtain the material thickened by shear, as a solid phase, synthetic silica Fumed (SF) and halloysite with average grain sizes of 7 nm and 300 nm, respectively, were used. The dispersant was poly (propylene glycol) with a molecular weight of 400 g / mol (PPG 400).

The solid phase accounted for 20 vol.%. the whole mass. The volume ratio of nanosilica to halloysite in the solid phase was 95: 5 and 99: 1, respectively. The masses were mixed in a vessel placed in a thermostat at a temperature of 54 ° C with a mechanical stirrer for 3 hours. The stirrer was rotated at a speed of about 100 revolutions per minute.

After the homogenization process, the ceramic slip masses were subjected to rheometric measurements on a plate-plate rheometer at a temperature of 25 ° C. The distance between the plates was 0.7 mm.

The set speed of the upper plate increased from 1 to 500 s ^-1 .

The obtained masses were characterized by the viscosity jump effect equal to 491 Pa-s (95: 5) and 336

-1 -1

Pa-s (99: 1) at a shear rate of 30.8 s ^-1 48.7 s ^{-1, respectively} .

P r z k ł a d 3.

In order to obtain the material thickened by shear, as a solid phase, synthetic silica Fumed (SF) and halloysite with average grain sizes of 14 nm and 300 nm, respectively, were used. The dispersant was poly (propylene glycol) with a molecular weight of 425 g / mol (PPG 425).

The solid phase accounted for 12% by volume. the whole mass. The volume ratio of nanosilica to halloysite in the solid phase was 97: 3 and 99: 1, respectively. Before combining with the rest of the reactants, the halloysite was subjected to a centrifugation process. The preparation of halloysite by centrifugation consisted in preliminary mixing of this powder with a mixture of ethanol with PPG 425 in a weight ratio of 2: 1 in a ball mill. A dispersion was a ^1/3 wt%, EtOH ^1/3% by weight of the liquid phase. The mixing process was carried out for 30 minutes at a speed of 300 revolutions per minute. Then, the suspension was transferred to sealed polyethylene tubes and subjected to a centrifugation process in a laboratory centrifuge for 30 minutes at a speed of 13,000 rpm. The purpose of this process was to remove adsorbed water on the surface of the powder grains. After the centrifugation process, the liquid was decanted from the sediment, and the halloysite was transferred to the crystallizer and left in the dryer until completely dry. The powder was then crushed in a mortar, sieved on a sieve with a hole size of 0.063 mm and poured into a sealed package.

The masses based on previously prepared halloysite, nanosilica and PPG 425 in appropriate volumetric ratios were mixed in a vessel placed in a thermostat at the temperature of 54 ° C with a mechanical stirrer for 3 hours. The stirrer was rotated at a speed of about 100 rpm.

After the homogenization process, the ceramic slip masses were subjected to rheometric measurements on a plate-plate rheometer at a temperature of 25 ° C. The distance between the plates was 0.7 mm.

The set speed of the upper plate increased from 1 to 500 s ^-1 .

The obtained masses were characterized by the viscosity jump effect equal to 293 Pa-s (97: 3) and 440

-1 -1

Pa-s (99: 1) with a shear rate of 15.4 s ^-1 9.7 s ^{-1, respectively} .

P r z k ł a d 4.

In order to obtain the material thickened by shear, as a solid phase, synthetic silica Fumed (SF) and halloysite with average grain sizes of 14 nm and 300 nm, respectively, were used. The dispersant was poly (propylene glycol) with a molecular weight of 725 g / mol (PPG 725).

The solid phase accounted for 12% by volume. the whole mass. The volume ratio of nanosilica to halloysite in the solid phase was respectively 90:10; 95: 5; 97: 3 and 99: 1. Before combining with the rest of the reactants, the halloysite was subjected to a centrifugation process. The preparation of halloysite by centrifugation consisted in preliminary mixing of this powder with a mixture of ethanol with PPG 725 in a weight ratio of 2: 1 in a ball mill. A dispersion was a ^1/3 wt%, EtOH ^2/3% by weight of the liquid phase. The mixing process was carried out for 30 minutes at a speed of 300 revolutions per minute. Then, the suspension was transferred to sealed polyethylene tubes and subjected to a centrifugation process

The purpose of this process was to remove the adsorbed water on the surface of the powder grains. After the centrifugation process, the liquid was poured off the sediment, and the halloysite was transferred to the crystallizer and left in the dryer until completely dry. The powder was then crushed in a mortar, sieved on a sieve with an opening size of 0.063 mm and poured into a sealed package.

The masses based on previously prepared halloysite, nanosilica and PPG 725 in appropriate volumetric ratios were mixed in a vessel placed in a thermostat at the temperature of 54 ° C by means of a mechanical stirrer for 3 hours. The stirrer was rotated at a speed of about 100 rpm.

After the homogenization process, the ceramic slips were subjected to rheometric measurements on a plate-plate rheometer at a temperature of 25 ° C. The distance between the plates was 0.7 mm. -1

The set speed of the upper plate increased from 1 to 500 s ^-1 .

The obtained masses were characterized by the viscosity jump effect equal to 341 Pa-s (90:10), 354 Pa-s (95: 5), 436 Pa-s (97: 3) and 553 Pa-s (99: 1) at the shear rates equal respectively

7.8 s ^-1 ; 7.8 s ^-1 ; 6.2 s ^-1 and 7.8 s ^-1 .

P r z k ł a d 5.

In order to obtain the material thickened by shear, as a solid phase, synthetic silica Fumed (SF) and halloysite with average grain sizes of 7 nm and 300 nm, respectively, were used. The dispersant was poly (propylene glycol) with a molecular weight of 725 g / mol (PPG 725).

The solid phase accounted for 12% by volume. the whole mass. The volume ratio of nanosilica to halloysite in the solid phase was 97: 3. Before combining with the rest of the components, the halloysite underwent a magnetic separation process. With the aid of a magnet, magnetic fractions such as Fe2O3, Fe3O4, TiO2 particles, amorphous iron hydroxides, magnetite, hematite and ilmenite were separated.

The mass based on previously prepared halloysite, nanosilica and PPG 725 was mixed in a vessel placed in a thermostat at a temperature of 54 ° C with a mechanical stirrer for 3 hours. The stirrer was rotated at a speed of about 100 rpm.

After the homogenization process, the ceramic slip was subjected to rheometric measurements on a plate-plate rheometer at a temperature of 25 ° C. The distance between the plates was 0.7 mm.

The set speed of the upper plate increased from 1 to 500 s ^-1 .

The obtained mass was characterized by the viscosity jump effect equal to 296 Pa · s at the shear rate equal to 12.3 s ^-1 .

P r z k ł a d 6.

In order to obtain the material thickened by shear, as a solid phase, synthetic silica Fumed (SF) and halloysite with average grain sizes of 80 nm and 300 nm, respectively, were used. The dispersant was poly (propylene glycol) with a molecular weight of 725 g / mol (PPG 725).

The solid phase accounted for 12% by volume. the whole mass. The volume ratio of nanosilica to halloysite in the solid phase was 97: 3. Before combining with the rest of the reactants, the halloysite was subjected to the process of magnetic separation and centrifugation. With the aid of a magnet, magnetic fractions such as Fe2O3, Fe3O4, TiO2 particles, amorphous iron hydroxides, magnetite, hematite and ilmenite were separated. Preparation halloysite by centrifugation was based on the initial mixing of the powder was mixed with ₁ Ethanol from PPG 725 in a weight ratio of 2: 1 in a ball mill. A dispersion was a ^1/3 Outgoing _2% weigh and EtOH ^2/3% by weight of the liquid phase. The mixing process was carried out for 30 minutes at a speed of 300 revolutions per minute. Then, the suspension was transferred to sealed polyethylene tubes and subjected to a centrifugation process in a laboratory centrifuge for 30 minutes at a speed of 13,000 rpm. The purpose of this process was to remove the adsorbed water on the surface of the powder grains. After the centrifugation process, the liquid was decanted from the sediment, and the halloysite was transferred to the crystallizer and left in the dryer until completely dry. Then the powder was ground in a mortar, sieved on a sieve with a hole size of 0.063 mm and poured into a sealed package.

The mass based on previously prepared halloysite, nanosilica and PPG 725 was mixed in a vessel placed in a thermostat at a temperature of 54 ° C with a mechanical stirrer for 3 hours. The stirrer was rotated at a speed of about 100 rpm.

After the homogenization process, the ceramic slip was subjected to rheometric measurements on a plate-plate rheometer at a temperature of 25 ° C. The distance between the plates was 0.7 mm.

The set speed of the upper plate increased from 1 to 500 s ^-1 . The obtained mass was characterized by a viscosity jump effect equal to 364 Pa · s at a shear rate of 7.8 s ^-1 .

Claims (10)

CLAIMS 1. Ceramic mass with expansion properties, containing silica dispersed in a liquid organic compound, characterized in that it comprises a mixture of nanosilica and halloysite powder, the proportion of halloysite being from 1 to 20% by volume. based on the volume of the solid phase, and the total solids concentration by weight is from 10 to 30 vol.%. 2. Mass according to claim The method of claim 1, wherein the halloysite powder has an average grain size from 3 to 400 nm. 3. Mass according to claim The method of claim 1, wherein the halloysite has previously undergone a magnetic separation process. 4. Mass according to claim The method of claim 1 or 3, characterized in that it contains halloysite prepared by mixing the powder with a mixture of C1-C3 alcohol with glycol and / or polyglycol, followed by centrifugation, drying and grinding. 5. Mass according to p. 4. The method of claim 4, characterized in that a mixture of C1-C3 alcohol with glycol and / or polyglycol in a weight ratio of 2: 1 is used in the process of preliminary preparation of halloysite, centrifugation is carried out for 10 to 40 minutes at a speed of 10,000-13,000 rpm. / min 6. Mass according to p. The method of claim 1, characterized in that it contains nanosilica obtained by the spraying method, with a nominal average grain size from 3 to 400 nm. 7. Mass according to p. The method of claim 1 or 6, characterized in that it contains nanosilica previously suspended in an organic solvent, and then subjected to a centrifuging and drying process. 8. Mass according to claim The process of claim 1, wherein the liquid organic compound is glycol and / or polyglycol. 9. Mass according to claim The process of claim 8, wherein the glycol is poly (propylene glycol). 10. Mass according to claim 9. The process of claim 9, wherein the poly (propylene glycol) has a molecular weight of 400 to 800 g / mol.