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Sayed Ibrahim Faculty at Technical University of Liberec, Department of Textile Technology Ph.D from Technical University of Liberec, Czech Republic Research Interest: Textile Technology and Quality Control Topic Characterization of Basalt Filaments in Longitudinal Compression Slide 2 CHARACTERIZATION OF BASALT FILAMENTS IN LONGITUDINAL COMPRESSION Ji Militk, Vladimr Kovai, Sayed Ibrahim Textile Faculty, Technical University of Liberec 461 17 Liberec, Czech Republic Slide 3 (approx. 8000 students) Faculty of Mechanical Engineering Textile Faculty Faculty of Education Faculty of Economics Faculty of Mechatronics Faculty of Architecture Technical University of Liberec Slide 4 Staff 120 teachers 1.MSc Studies (technology, material engineering, clothing) 800 2.BSc Studies (chemistry, marketing, design, mechanics, clothing) 600 3.Part time studies (textile technology) 60 4. Ph.D. (technology, material engineering, clothing) 60 Technical University of Liberec Textile Faculty Slide 5 Basics of textile engineering Fibers are the fundamental and the smallest elements constituting textile materials. The mechanical functional performance of garments are very much dependent on the fiber mechanical and surface properties, which are largely determined by the constituting molecules, internal structural features and surface morphological characteristics of individual fibers. Scientific understanding and knowledge of the fiber properties and modeling the mechanical behavior of fibers are essential for engineering of clothing and textile products. Molecular properties Fiber Properties Yarn Properties Fabric properties Fiber Structure Yarn Structure Fabric Structure Garment Structure Demands of using textiles in industrial application are very high and risk should be minimum i.e. precise characterization Slide 6 OUTLINE Basalt rocks Fibers formation Basic properties Compressive creep Strength statistics Tempering Textile structures Fibrous fragments Slide 7 Basaltic rocks Basalt is generic name for solidified lava which poured out the volcanoes Basalt is 1/3 of earth Crust Basaltic rocks are melted approximately in the range 1500 1700 C. When this melt is quickly quenched, it solidificated to glass like nearly amorphous solid. Slow cooling leads to more or less complete crystallization, to an assembly of minerals. Augite Plagioclase Olivine Slide 8 Basalt composition Chemical composition: silicon oxide SiO 2 (optimal range 43.3 47 %) Al 2 O 3 (optimal range 11 13 %) CaO (optimal range 10 12 %) MgO (optimal range 8 11 %) Other oxides are almost always below 5 % level Essential minerals plagiocene and pyroxene (augite) make up perhaps 80% of basalts Slide 9 Fiber Forming Process Similar to E-glass forming Except: Only one material, crushed rock No flux like boric oxide added for processing Higher melting temperature 1400 C + vs. 1200 C Harder to process, but better properties (Silane-based sizing agent is added to facilitate post processing) Basalt Furnace 1) Crushed stone Silo, 2)Loading station, 3) Transport system, 4)batch charging station, 5) Initial melt zone, 6) Secondary contrlled heat zone, 7) Filament forming, 8) Sizing applicator, 9) Strand formation, 10) Fiber tensioning, 11) Winding Slide 10 Filaments formation Classical procedure Heat transfer from walls to center High power (4 kWh/kg) Long pre heating 8 hours Spinneret materials (Platinum, rhodium) Microwave heating Heat transfer from center to walls Low power (1 kWh/kg) Short pre heating 3 hours Spinneret materials (ceramics) Melt after 5 min at 1300 o C Slide 11 Properties of Basalts Basalts are more stable in strong alkalis that glasses. Stability in strong acids is low Basalt products can be used from very low temperatures (about 200 C) up to the comparative high temperatures 700 800 C. At higher temperatures the structural changes occur. Slide 12 Basalt Glass Comparison PropertyBasaltE-glass Diameter[ m] 8.639 - 13 Density[kgm -3 ]27332540 Softening temp. [ C] 960840 Typical composition of basalt fiber vs. E-glass fiber Chemical components Basalt Weight % E-Glass Weight % SiO 2 (silica)5855 Al 2 O 3 (alumina)1715 Fe 2 O 3 (ferric oxide)100.3 CaO818 MgO43 Na2O2.50.8 TiO 2 1.1- K2OK2O0.80.2 B2O3B2O3 -7 F-0.3 standard E-glass fibres from non-alkali glass (to 1% alkali), manufactured at 1550 o C Manufacturing cost is between E-glass and S- glass Sio 2 Al 2 O 3 CaO MgO B 2 O 3 Slide 13 Applications The basalt-reinforced PP composite meets disposal requirements without incinerator contamination issues Slide 14 Samples Preparation The marbles and filament roving are prepared. From marbles the thick rods were prepared by grinding. The roving contained 280 single filaments are used. Mean fineness of roving was 45 tex. Slide 15 Fibers Strength The cumulative probability of fracture F(V, ) depends on the tensile stress level and fiber volume V. F(V, ) = 1 - exp(- R( )) The specific risk function R( ) for Weibull distribution (conditional failure function) R( ) = [( - A)/B] C A is lower strength limit, B is scale parameter and C is shape parameter model (WEI 3) Shape parameter, location parameter, scale parameter. Slide 16 Strength distributions For brittle materials A = 0 (model WEI 2). Kies more realistic risk function (model KIES) R( ) = [( -A)/(A1- ) ] C Here A1 is upper strength limit. For brittle materials A = 0 (model KIES2). Phani (model PHA5) R( ) = [( -A)/B1] D / [(A1- )/B ] C ). Gumbell model (GUM) R( ) = exp[( -A)/(B)] Slide 17 Statistical analysis Main aim of the statistical analysis is specification of R( ) and parameter estimation based on the experimental strengths ( i ) i=1.....N. Based on the preliminary computation it has been determined that for basalt fibers strength the Weibull distribution is suitable Slide 18 Testing The individual basalt fibers removed from roving were tested. The loads at break were measured under standard conditions at sample length 10 mm. Load data were transformed to the stresses at break i [GPa] Sample of 50 stresses at break Slide 19 Maximum likelihood estimation When i i=1,...N are independent random variables with the same probability density function f( ) = F( i, a) the logarithm of likelihood function has the form ln L = ln f(( i, a) The a are parameters of corresponding risk function. The MLE estimators a* can be obtained by the maximization of ln L(a). Slide 20 Parameter estimates ModelA [GPa]B [GPa]C [-]ln L(a*) WEI30.06410.2301.37033,50 WEI2-0.3011.82929.164 The differences between three and two parameters Weibull distribution are identified by the values of maximum likelihood function ln L(a*). The three-parameter Weibull distribution was selected as suitable for glass and tempered basalt samples as well Slide 21 Failure mode Modes of fracture - scanning electron microscopy. Untreated BasaltLongitudinal view Slide 22 Mechanism of fracture Surface is very smooth without flaws or crazes Fracture occurs due to nonhomogenities in fiber volume (probably near the small crystallites of minerals) glass basalt Slide 23 Thermal exposition I Tempering temperature 50, 100, 200, 300 o C was used. Time of exposition 60 min. Thermal exposition influence on the ultimate mechanical properties and dynamic acoustical modulus (DMA) has been evaluated. tensile strength [N.tex-1] deformation to break [%] dynamic acoustic modulus [Pa] (determined from sound wave spread velocity in the material) For 300 o C tempering only results statistically significant drop of strength and dynamic acoustical modulus. The changes of these properties are based on the changes of crystalline structure of fibers. Slide 24 Resonance frequency technique (RFT) Acoustic Pulse Method (APM) Sample Slide 25 Thermal exposition II Basalt filament roving tempered at T T = 20, 50, 100, 200, 300, 400 and 500 o C in times t T = 15 and 60 min. The dependence of the roving strength on the temperature exhibits two nearly linear regions. One at low temperature to the 180 o C with nearly constant strength and one up to the 340 o C with very fast strength drop Slide 26 Thermal exposition III 1. Tempered basalt fibers from roving were tested. 2. The apparatus based on the torsion pendulum principle was used. (fiber of length l o hanged with pendulum period P and amplitude A, successive oscillations were measured, the shear modulus of circular fiber is calculated) 3. The shear modulus G =11-21 GPa is comparatively high. The prolongation of tempering leads to high drop of G. lolo Slide 27 Thermal exposition IV Fragility - ratio of critical loop diameter Dc and fiber diameter d Fr = Dc / d critical loop diameter - by deformation of basalt loop under microscope to failure temperature 50, 150, 250, 350 o C was evaluated time of exposition 60 min In accordance with assumption are fragilities increasing function of tempering temperature the quality or state of being easily broken or destroyed Slide 28 Thermo mechanical analysis (TMA) In TMA the dimensional changes are measured under defined load and chosen time Special device TMA CX 03RA/T has been used Sample is placed on the movable holder (in oven) connected with displacement sensor, which measures dimensional changes Slide 29 Thermal expansion Dependence of basalt rod height on the temperature was measured.( heating rate 10 deg min -1, compressive load 10 mN). The coefficients of thermal expansions a for region below and above T g L = L g + a 1 *(T - T g )for T below T g L = L g + a 2 *(T - Tg)for T above T g Parameter estimates: T g = 596.3 o C, a 1 = 4.9 10 -6 deg -1, a 2 = 19.1 10 -6 deg -1. rate of material expansion as a function of temperature DMA Slide 30 Compressive creep For the basalt rods and linear composites the dependence of sample height L on the time t were measured. L = L p + L 1 exp (-k 1 * t) + L 2 exp(-k 2 * t) Parameters L p, L 1, L 2, k 1 and k 2 estimated by LS The maximum dilatation D = L 1 + L 2 Half time of dilatation t 1/2 (it is time for which is dilatation equal to L p + (L 1 + L 2 )/2. Slide 31 Compressive creep parameters T [ o C] D[mm] t 1/2 [s] D [mm] t 1/2 [s] 30 50 100 250 300 0.003 0.028 0.053 0.035 - 145.1 36.90 29.80 41.10 - 0.015 - 0.008 - 0.042 16015 - 21.30 - 51.7 Slide 32 Non-isothermal compressive creep The responses of basalt to the compressive loads under non-isothermal conditions were investigated from creep type experiments. The load was 200 mN. For the basalt rod the dependence of sample height L on the temperature T (increased linearly with time t )were measured. Starting temperature was T o = 30 o C and rate of heating was 10 o C/min. For avoiding the initial The dilatation d i = L o L has been recorded Slide 33 Data Smoothing The experimental points were smoothed by Reinsch smoothing spline (parameter s = 1) deltatation temperature Slide 34 Creep model I From isothermal experiments is deduced that the rate of creep only is markedly temperature dependent. The rate of height changes can be expressed by differential equation K is the rate constant is sample height in equilibrium. Function f(.) is creep rate model. Slide 35 Creep model II The classical reaction kinetics the creep rate can be expressed in the form where n is constant (order of reaction). For n=1 the simple exponential model of creep (rate process of first order) results. Temperature dependence of the creep rate constant K Slide 36 Creep model III In non-isothermal conditions it is assumed that temperature dependent is rate constant only By the formal integration of this eqn. for exponential type model (n = 1) the following relation results Slide 37 Creep model IV For the case of linear heating during creep is valid Symbol T o denotes initial temperature and G(x) is the integral where is rate of heating Slide 38 Approximation of integral Simple and precise approximation of temperature term has the form The relative error of approximation is for E/RT