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Study of effect Ti[O.sub.2] additive on the properties of glass-ceramic products from soda lime glass.

INTRODUCTION

Glass is a homogeneous material with anamorphous molecular structure (non-crystalline). Glass consider a fourth state of material that associates the random molecular structure of liquids with the rigidity of crystals. It is often described as a glassy orvitreous state. Glass must be around5 times as strong as steel for the nature of its atomic bonds. The most common (90% of glass made)is soda-lime Silica glass and least cost form glass. It generally consist of (60-75%) silica, (12-18%) soda and (5-12%) lime. Its resistance to sudden changes of temperature and high temperatures are not good and resistance to corrosive chemicals is only fair. The glass transition temperature for soda-lime glass is (500-600[degrees]C), while melting temperature is about (1000[degrees]C)[4]. The glasses of the system ([Na.sub.2]O-CaO-Si[O.sub.2]) are employed in various applications such components of automobiles, furniture, packages, houses, etc. nevertheless, its fragility is an aspect of industrial and technological interest.

It can be considered as a development of various techniques among are the adding of metal either one or more oxides of the alkaline type. The Ti[O.sub.2]made enhancement in the mechanical properties of glassy systems, which have solved the formation problem of cracks and the growing of surface crystalline layer is slowed down in its primary stage as occurs in the systems (CaO-[P.sub.2]O[1/5])and (MgO-CaO-Si[O.sub.2]-[P.sub.2][O.sub.2]), materials very important in the industrial and biological field to elaborate artificial teeth and bones [9].

Glass ceramics can be described as polycrystalline formed materials, as shown in figure(1). Glasses are melted, fabricated to shape and thermally converted to a predominantly crystalline ceramic through the controlled nucleation and crystallization of glass, therefore, the glass ceramic process is basically a simple thermal process [15]. Powder processing methods can also be used to form glass-ceramics by which glass frits are sintered and crystallized. This technique somewhat spreads the variety of possible glass-ceramic compositions. It also tolerates for surface as well as internal nucleation. The devitrifying solder glasses are examples of powder-processed glass-ceramics [2]. The crystallization is a process by which regular periodic crystalline structure is formed from the random liquid structure of glass. It is usually consist of two independent processes. The first process is the nucleation, by which the crystallization centers are formed, and the second process is the crystals growth on these formed centers. The primary nuclei composition does not vary from that of the main crystalline phase in homogeneous nucleation, while, the crystallization of the glass in heterogeneous nucleation is induced by introduction foreign nuclei which named nucleating agent. The nucleating agent, which is usually an oxide, metal or fluoride, is combined in the batch and becomes an essential part of the glass through heat treatment or melting. Nucleating agents are commonly employed in most production processes of glass-ceramic. The most commonly used nucleating agents are (Ti[O.sub.2]), (Zr[O.sub.2]) and ([P.sub.2][O.sub.5]). The Pt group and noble metals, and fluorides are also used [14]. Many researchers have studied the effect of adding some materials onto properties of glass ceramics such as Sascha et. al. tested the effect of adding ([P.sub.2][O.sub.5])on the crystallization and microstructure of glass-ceramics using high temperature[10], Toshihiro et al. prepared the machineable glass-ceramics via ([P.sub.2] [O.sub.5]) as glass former with (Ti[O.sub.2]) as a doping material [13], Sutatipstudied the effect of adding (CaO) on the thermal parameters, physical properties, phase formation and microstructures properties of ([P.sub.2][O.sub.5]-CaO-[Na.sub.2]O) glass ceramics[12].

In this study, (Ti[O.sub.2]) used as nucleating agent (heterogeneous nucleation).Titanium dioxide (Ti[O.sub.2]) is white solid inorganic material and thermally stable, non-flammable, low dissolution and not categorized as dangerous material depending on the United Nations' (UN) Globally Harmonized System of Classification and Labeling of Chemicals (GHS). Ti[O.sub.2] present naturally in some types of mineral sands and rocks. (Ti[O.sub.2]) is chemically inert.(Ti[O.sub.2]) has been employed for many years in a large range of consumer and industrial goods including adhesives, coatings, paints, rubber and plastics, paperboard and paper, coated fabrics and textiles, printing inks, ceramics, catalyst systems, roofing materials, floor coverings, food colorants, water treatment agents, pharmaceuticals and cosmetics, and in automotive products, etc. [5].

When the crystallites of (Ti[O.sub.2])are present in the glass ground, the (Ti[O.sub.2]) crystallites distributed in the glass ground will produce a steady characteristic property even with surface polishing [7]. It is very difficult to get selective crystallization of (Ti[O.sub.2]), since a crystal of (Ti[O.sub.2]) makes as a nucleus of another crystalline phases and also because it makes other crystal structure with another oxides which form the glass, such as Si[O.sub.2] or [Al.sub.2][O.sub.3]. It can suggest(Ti[O.sub.2]) glass-ceramic as an important material for some applications, such as a photocatalytic transparent substance in which precipitated (Ti[O.sub.2]) crystallites will represent permanent photocatalytic property because of the fully dispersion. Other application is employas an optical element in a lasing optical device. Thenano-crystallites of (Ti[O.sub.2]) in the glass ground can restrain light, which is interesting and suitable for random lasing, because the refractive index of (Ti[O.sub.2]) is (2.52 (anatase) ~ 2.728 (rutile)) [6]. Glass-ceramics are also employed as biomaterials in two diverse areas (as in glass-ceramic containing calcium phosphate and Ti[O.sub.2]): one of them, they are employed as very durable materials in healing dentistry and other, they are used as bioactive materials for the replacement of hard tissue. Dental restorative materials are materials which reinstate the normal tooth structure (both in function and shape), show toughness in the oral environment, high strength and wear resistance[11].

Experimental Work:

In this study, the samples from soda lime glass (as powder with particle size approximately 60 [micro]m) and different percentages of titanium dioxide (Ti[O.sub.2] with particle size approximately 15 [micro]m) were made by using powder method and then made tests on the produced samples which include physical, mechanical and thermal tests.

Materials Preparation:

Materials preparation includes weighing and mixing four types from soda lime glass with different percentages of titanium dioxide (nucleating agent). These types are explained in Table 1. The weighing process was carried out by using a sensitive balance which has accuracy(0.0001 g) type : mettler AE200 while the mix process was made by using electrical mixer.

Samples Formation:

Single direction Semi-dry pressing method was used in samples formation by using hydraulic uniaxial pressing machine at a pressure of (80MPa). Press force for all samples was (25 KN) by using Stainless-Steeldie with (d= 20mm). Liquid paraffin wax was used as the lubrication to reduce the friction between the two parts of the die and to prevent adhesion between the particles with die wall during getting out the sample from the die after the pressing. Polyvinal alcohol (PVA) binder was used to prepare the samples, the percentage required of (PVA) to each sample (10%) from sample weight as the pressing is semi-dry. After that the samples were dried at temperatures (110[degrees]C) for four hours to remove the moisture from the samples.

Heat Treatment:

Controlled heat treatment was made on all samples to promote the process of crystallization and the transformation of the glass into a glass-ceramic. The thermal cycle, which carried out on the sample, included two stages of heat treatment which it nucleation stage and crystallization stage as shown in figure(2). An electrical furnace was used for heat treatment in this study. In nucleation stage, the specimens were heated to the nucleation temperature (370[degrees]C) with rate of heating (5[degrees]C/min)and held for (2 hours) of time in order to form the nucleus from nucleating agent(Ti[O.sub.2]). After that the nucleated specimens were heated up to the crystallization temperature (550[degrees]C) and held for (2 hours) of time to grow the formed nucleusto crystals and to transform the glass into glass--ceramic.

Tests:

The glass-ceramic samples were tested by several tests which include mechanical, physical and thermal tests as follows:

1-Mechanical Properties:

A-Compressive Strength:

The general testing machine was used to measure the compressive strength for samples. Each test result is the average of three test samples. This test is done according to the ASTM (C 773-88) standard [1]. Compressive strength is calculated from the equation (1).

[[??].sub.c] = F / [A.sub.r] (1)

where:

[[??].sub.c]= Compressive strength in (MPa).

F = Applied load until fracture (N).

[A.sub.r] = Cross section area ([mm.sup.2]).

B-Hardness:

The hardness of glass-ceramic samples were tested by Vickers hardness. Vickers hardness values were measured on polished surfaces by Vickers indentation technique at a 9.8 kg load applied for (10) seconds. The hardness values were obtained from an average of (3) indents on each of the three samples. Equation (2)used to calculate Vickers hardness[1].

Hv = 1.854 x P/[a.sup.2] (2)

Where:

Hv = Vickers hardness (kg/[mm.sup.2])

P = the indentation load (kg).

a = half the indentation diagonal (mm).

2-Physical Properties:-

A-Visual Properties:

Visual properties for samples (the color and the outer shape) were tested. The visual test carried out to ensure that the sample is suitable and there are not any cracks or deformations which may effect on the physical and mechanical tests.

B-Density and Porosity:

The glass-ceramic samples density were determined by Archimedes technique. The glass-ceramic samples were boiled in water for (4) hr in order to fill the pores with steam. The samples were cold to ambient temperature. The suspended sample mass in water was determined ([m.sub.s]) and the water-saturated mass ([m.sub.w]). The water-saturated mass was done by drying the surface of the sample with a paper towel then determining its mass. An average of three readings was taken for each mass (both [m.sub.s] and [m.sub.w]). The samples were then dried in the furnace at (105[degrees]C) for (25) minutes and the dry samples mass was measured (ma). Density values were obtained from an average of three samples. The density and open porositywere calculated by using equation (3) and equation (4) respectively. This test is done according to the (ASTM C373-88) standard[1, 8].

[rho] = [m.sub.d] [[rho].sub.water]/[m.sub.s] - [m.sub.w] (3)

[P.sub.o] = [m.sub.w] - [m.sub.d]/[m.sub.w] - [m.sub.s] x 100 (4)

Where:

[rho] = the bulk density (g/[cm.sup.3])

[P.sub.o] = percentage of the open porosity.

[[rho].sub.water] = the density of water (g/[cm.sup.3]).

[m.sub.d] = the dry mass (g).

[m.sub.s] = mass of the sample suspended in water (g).

[m.sub.w] = the water saturated mass (g).

C-X-ray Diffraction:

The heat treated glass-ceramics samples were tested by X-ray diffraction analysis of the powder crystalline samples to identify the crystalline phases developed by crystallization of the glass. The glass--ceramic samples were grounded by a mortar and pestle into a fine powder that was tested by XRD. The X-ray patterns were obtained using a (SHIMADZU XRD--6000). A Cu anode voltage of (40 kv) and currents of (30 mA) were applied. The X-ray diffraction wasachieved at continuous scan mode with range(2[theta]) between (20[degrees]) and (60[degrees]) and a step size of (2[theta] =0.0200[degrees]). A scanning speed of (5 degrees ([theta])/min) was employed for the analyses.

3-Thermal Tests (Differential Scanning Calorimetry (DSC)):

Differential scanning calorimetry (DSC) was employed to test the thermal transitionsof the glass-ceramiccompositions including glass transition temperature (Tg) and crystallization temperature (Tc). The (DSC) analysis was performed within a temperature range from (0[degrees]C to 550[degrees]C) at a heating rate of (10[degrees]C/min). The (DSC) device is connected to a control and program unit that show the data. Specimen (10 mg) from the glass-ceramic powder was put in an aluminum pan of (DSC) device, with an empty aluminum pan as a reference,(Tg and Tc) values were determined on (DSC)curves. This test was made for all the prepared compositions.

RESULTS AND DISCUSSION

The present study was conducted to evaluate effect of the (Ti[O.sub.2]) addition to soda lime glass on the physical, mechanical and thermal properties of the glass-ceramic which produced from it.

Figure(3) shows the compressive strength of the produced glass-ceramic samples from soda lime glass with different percentages of titanium dioxide (0,3,6 and 10% wt. of Ti[O.sub.2]). It has been shown that the increasing of compressive strength happen with increasing of additive percentage of Ti[O.sub.2]. Also the hardness for samples increase with increasing of additive percentage of (Ti[O.sub.2]) as shown in Figure(4). An improving on the mechanical properties of the produced sampleshad happencompared with the original glass, because of the crystalline phases formation in the glass matrix, which represented by the phase ([Na.sub.2][Ca.sub.2][Si.sub.3][O.sub.9] at 6% wt. Ti[O.sub.2]) and anatase phase at (10% wt. Ti[O.sub.2]) as shown in the X-ray diffraction analysis which means the increase in the chemical bonds between the material particles and the decrease the pores between them which makes the glass network more rigid, also because increasing the glass transition temperature of samples with increasing of(Ti[O.sub.2]) containas shown in the (DSC) curves, which lead to increase in mechanical strength of the samples.

In the visual properties test, the samples without (Ti[O.sub.2]) were transparent while the samples with (10% wt.) of (Ti[O.sub.2]) were translucent and tend to the white color gradually with increase the(Ti[O.sub.2]) percentage because there was a difference in refractive index between the precipitated crystallites and the surrounding glass matrix, which lead to lose of transparency of the glass because of light scattering by (Ti[O.sub.2]) crystallites with a large refractive index. Also the edges curvature was observed on the outer shape of the glass-ceramic specimens as a result to the heat treatment.

Figure (5) shows effect of the(Ti[O.sub.2]) percentage on the bulk density of glass- ceramic specimens, where density of the samples increases with increasing of (Ti[O.sub.2]) percentage. While Figure(6) shows effect of the(Ti[O.sub.2]) percentage on the porosity of glass- ceramic specimens, where porosity of the samples decreases with increasing of (Ti[O.sub.2]) percentage. This may be attributed to the closer packing of atoms to the formation of strong structure, where the titanium forms some new interconnections within the glass network because it has a large electrical charge (+4).Also it is shown that the density of the glass- ceramic was higher than that of the equivalent glass (soda lime glass). It may be attributed to the fact that, in most cases, the densities of crystals are higher than those of the glass with the same composition because the higher atomic structural compaction [3].

Figures(7, 8, 9 and 10) show the X-ray diffraction patterns for the produced glass ceramic samples from soda lime glass with different percentages of titanium dioxide (0,3,6 and 10 % wt. of Ti[O.sub.2]). The X-ray diffraction analysis shows present of crystalline phases in the glass matrix, this means production of glass ceramic from the prepared compositions. The important feature of all these figures is the increase of the addition weight percent of (Ti[O.sub.2]) lead to produce a peak related to this additive. Figure(7) shows the X-ray analysis for the prepared glass sample without (Ti[O.sub.2]). In Figure (8) X-ray analysis for composition (3% wt. of Ti[O.sub.2]), the reflection at (28[degrees])identified the internal standard of (Si), the reference data for the interpretation of X-ray diffraction patterns were obtained from the ASTM X-ray diffraction file index and from other publications. Figure(9) X-ray analysis for composition (6% wt. of Ti[O.sub.2]) shows reflection at (33.7[degrees])which identified the phase ([Na.sub.2][Ca.sub.2][Si.sub.3][O.sub.9]). In Figure(10) X-ray analysis for composition (10% wt. of Ti[O.sub.2]), a peak in (27.5[degrees]) (2[theta]) identified the present of (Ti[O.sub.2]) (anatase) phase. The addition of more powder content leads to slightly decrease of the intensity, as shown this difference in intensity between Figures (7 and 10).

Glass transition temperature (Tg) and crystallization temperature (Tc) were measured from temperature of the maximum peak of (DSC) curves for the glass- ceramic samples as shows in Figures (11, 12, 13 and 14). The value of glass transition temperature and crystallization temperature increased for the glass- ceramic samples with increase of (Ti[O.sub.2]) additive percentage as shown in Figure(15). The (DSC) peak shifted toward higher temperature when compared with the original glass Figure(11), the increase was predictable because of the fact that (Ti[O.sub.2]) is known to increase the glass viscosity and strengthen the glass network because the melting temperature of (Ti[O.sup.2]) is higher than that of all components of the original glass.

Conclusions:

1. Production of the glass-ceramic from the soda lime glass with different (Ti[O.sub.2]) percent (0, 3, 6, 10% wt.) was done successfully and the (XRD) patterns of the prepared samples proved that.

2. The compressive strength and hardness increase with increasing of additive percentage of (Ti[O.sub.2]) and that is an improving in the mechanical properties of the produced glass-ceramic specimens.

3. The porosity values of the prepared samples decrease with increasing additive percentage of (Ti[O.sub.2]), while density of the samples increases with increase additive percentage of (Ti[O.sub.2]).

4. The glass transition temperature (Tg) and crystallization temperature (Tc) increase when the (Ti[O.sub.2]) additive percentage increase.

5. The prepared samples without (Ti[O.sub.2]) were transparent while the samples with (10% wt.) of (Ti[O.sub.2]) were translucent and tend to the white color gradually with increase the(Ti[O.sub.2]) percentage, also the edges of glass ceramic samples were curved as shown in the outer shape.

REFERENCES

[1.] ASTM annual book of standards., 1988. C 773-88 and C 373-88,.

[2.] Charles, A-H., 2001. Hand book of Ceramics Glasses and Diamonds. McGraw-Hill Companies Inc.

[3.] Cumpston, B., F. Shadman, S. Risbud, 1992. Utilization of coal--ash minerals for technological ceramics. J. Mater. Sci., 22(6): 1781-84.

[4.] Frank, S., 1998. Science A Resource for Glass. The Corning Museum of Glass Education Dept. Education Coordinator.

[5.] Gamer, A.O., et al., 2006. The in vitro absorption of microfine zinc oxide and titanium dioxide through porcine skin. Toxicology in Vitro, 20:301-307.

[6.] Hirokazu, M., T. Yoshihiro, F. Takumi, 2010. Glass-Ceramics Containing Nano- Crystallites of Oxide Semiconductor. Ceramic Materials, WilfriedWunderlich (Ed.), ISBN: 978-953-307-145-9.

[7.] Hosono, H., Y. Sakai, M. Fasano, Y. Abe1990. Preparation of monolithic porous titania silica ceramics. J. Am. Ceram. Soc., 73(8):2536-2538,

[8.] Kaya, Guray, 2013. production and characterization of self- colored dental zirconia blocks . Ceramics International.

[9.] Parra, S.M., A. Alvarez, L.C. Torres, E.M. Sanchez, 2009. Crystallization Kinetics of a soda lime silica glass with Ti[O.sub.2] addition. Investigation, 55(1): 32-37.

[10.] Sascha, C., S. Marcel, H. Wolfram, R. Volker, 1999. The effect of P2O5 on the crystallization and microstructure of glass-ceramics in the SiO2-Li2O-K2O-ZnO-P2O5 system. Journal of Non-Crystalline Solids 263 and 264.

[11.] Sukaina, I., 2010. Development and characterization of calcium phosphate glasses and glass-ceramics containing fluorine and titanium. Thesis in Biomaterials, Department of Metallurgy and Materials, University of Birmingham.

[12.] Sutatip, T., K. Pengpat1, G. Rujijanagul, S. Eitssayeam, S. Punyanitya, T. Tunkasiri, 2010. Effects of CaO on Properties of P2O5-CaO-Na2O Glasses and Glass Ceramics. Journal of Metals, Materials and Minerals, 20(3): 173-177.

[13.] Toshihiro, K., S. Sawada, M. Nogami, 2001. Preparation of Machineable Glass-Ceramics in the Na2O-CaO-TiO2-P2O5 System. Journal of Ceramic Society of Japan, 109(9): 719-721.

[14.] Weyl, W.A., 1960. Nucleation, crystallization and glass formation. Sprechsaal, pp: 128-36.

[15.] Wolfram, H., B. George, 2002. Glass-Ceramic Technology. Book is published and distributed by The American Ceramic Society.

(1) Dr. Hussein Talab and (2) Marwa Marza

(1) Lecturer, Department of Ceramic and Building Materials Engineering, College of Materials Engineering, University of Babylon, hila, Iraq,

(2) Assistant lecturer, Department of Ceramic and Building Materials Engineering, College of Materials Engineering, University of Babylon, hila, Iraq,

Received 1 April 2017; Accepted 18 June 2017; Available online 2 July 2017

Address For Correspondence: Dr. Hussein Talab, Lecturer, Department of Ceramic and Building Materials Engineering, College of Materials Engineering, University of Babylon, hila, Iraq.

Caption: Fig. 1 Schematic representations of (A) glass, (B) crystal and (C) glass-ceramic (Wolfram, 2002).

Caption: Fig. 2: Shows the thermal cycle which made to the formed samples.

Caption: Fig. 3: Shows effect of the (Ti[O.sub.2]) additive %wt. on compressive strength of the glass-ceramic samples.

Caption: Fig. 4: Shows effect of the Ti[O.sub.2] additive %wt. on Vickers Hardness of the glass-ceramic samples.

Caption: Fig. 5: Shows effect of the Ti[O.sub.2] additive %wt. on bulk density of the glass-ceramic samples.

Caption: Fig. 6: Shows effect of the Ti[O.sub.2] additive %wt. on apparent porosity of the glass-ceramic samples.

Caption: Fig. 7: Shows the X-ray diffraction pattern for the glass sample without (Ti[O.sub.2]).

Caption: Fig. 8: Shows the X-ray diffraction pattern for the glass-ceramic sample with (3% wt. of Ti[O.sub.2])

Caption: Fig. 9: Shows the X-ray diffraction pattern for the glass-ceramic sample with (6% wt. of Ti[O.sub.2])

Caption: Fig. 10: Shows the X-ray diffraction pattern for the glass-ceramic sample with (10% wt. of Ti[O.sub.2]).

Caption: Fig. 11: Shows (DSC) curve for the glass sample without (Ti[O.sub.2]).

Caption: Fig. 12: Shows (DSC) curve for the glass-ceramic sample with (3% wt. of Ti[O.sub.2]).

Caption: Fig. 13: Shows (DSC) curve for the glass-ceramic sample with (6% wt. of Ti[O.sub.2])

Caption: Fig. 14: Shows (DSC) curve for the glass-ceramic sample with (10% wt. of Ti[O.sub.2]).

Caption: Fig. 15: Shows effect of the (Ti[O.sub.2]%wt.) on glass transition temperature (Tg) and crystallization temperature (Tc) of the glass-ceramic samples.
Table 1: Shows the percentage and the weight of soda lime glass and
titanium dioxide in samples

Sample no.   Sample weight   Soda lime glass   Titanium
             (gm)            %                 dioxide %

1            9               100               0
2            9               97                3
3            9               94                6
4            9               90                10

Sample no.   Soda lime glass weight   Titanium dioxide
             (gm)                     weight(gm)

1            9                        0
2            8.73                     0.27
3            8.46                     0.54
4            8.1                      0.9
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Author:Talab, Hussein; Marza, Marwa
Publication:Advances in Natural and Applied Sciences
Article Type:Report
Date:Jul 1, 2017
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