Research on Affect Factors of Diffusion Coloration of High Borosilicate. Glass

Transcription

1 Journal of Materials and Applications 3:1 (214) Research on Affect Factors of Diffusion Coloration of High Borosilicate Glass Xingke Du, Yanyan Jiang, Bing Xie, Yanan Li School of Textile and Material Engineering, Dalian Polytechnic University, Dalian, China Abstract: The brown glass with smooth surface has been prepared by coloring its surface with ion diffusion of silver and copper, and the substrate is high borosilicate glass. Research the influence of different factors on the coloring effect of glass surface and determine the optimum process conditions under which brown coloration should be obtained by testing and analyzing the light transmittance, dominant wavelength and color purity of samples. Experimental results show that a better coloring effect can be achieved when the mass of AgNO 3 and CuSO 4 accounts for 7% of the color paste, the mass ratio of AgNO 3 and CuSO 4 is 1:5, and the heat treatment is 62 for 9min under a reducing atmosphere. Micelles with a diameter of several micrometers to dozens of microns on the surface of samples can be found by scanning electron microscopy (SEM), most present regular spherical, but few irregular strip. Energy dispersive X-ray spectra (EDS) analysis further indicates that the main components are Ag and Cu. The colored portion of the glass has excellent hot corrosion resistant performance. Key words: high borosilicate glass; ion diffusion; coloration; process conditions 1. Introduction Ion diffusion coloration on the glass surface has been gradually applied into production, and especially used more and more in high-end vessels, decorative glass and crafts. It s an important coloring method of glass surface because of the durable and non-shedding color, distinct printing effect and simple process[1-3]. Diffusion coloration with silver and copper ions is widely used in the printing of identification, scale, pattern and words of glass measuring instruments as well as the production of crafts. However, this method is usually used for the coloration of sodium calcium silicon glass, while application in high borosilicate glass is very rare. It is determined by the composition of high borosilicate glass. First, there is little alkali metal ion especially sodium ion in high borosilicate glass, making it hard for ion exchange reaction. As a result, coloring ions are not easy to enter the glass. Second, high borosilicate glass is essentially free of reduction compositions such as arsenic, antimony, ferrous, etc, which makes it difficult for the chromogen of coloring ions[4]. High borosilicate glass has a wide range of applications in high-grade daily-use glass, optical glass, precision instruments glass, lamps and lanterns glass because of its uniquely fine properties such as low expansion coefficient, high glass strength and softening point temperature, strong thermal conductive capability and good mechanical performance[5]. Hence, it gains a great application value when the simply operated method of diffusion coloration can be applied to high borosilicate glass. In this study, the brown glass with smooth surface was prepared by coloring high borosilicate glass with ion diffusion of silver and copper. It solved the problem of cumbersome process and non-ideal coloring effect when the method of ion diffusion coloration was applied to high borosilicate glass. The influence of different factors 17

2 3:1 (214) Journal of Materials and Applications on coloring effect was studied and the optimum technological conditions under which brown glass can be obtained were determined by adjusting the content and proportion of two kinds of coloring agents in paste and changing process conditions such as heat treatment temperature, time and atmosphere. 2. Experimental 2.1 Sample preparation Materials used in the experiment were dextrin powder, sodium hydroxide (NaOH), silver nitrate (AgNO 3 ), copper sulfate (CuSO 4 ), ferrous sulfate (FeSO 4 ), zinc powder (Zn), carbon powder (C), glycerol and deionized water. All above were analytical reagents. Color paste preparation: NaOH aqueous solution was prepared, then dextrin powder was added to reconcile into a paste-like (agglomerate and bubbles were not allowed). AgNO 3, CuSO 4 and FeSO 4 were added sequentially, and strengthen grinding stirring to prevent caking or granulated. An appropriate amount of zinc powder and carbon powder were added, then the mixture was stirred until smooth. There was heat release this moment. Glycerol was added after being cooled. The prepared paste was evenly coated on the surface of a clean high borosilicate glass, then it was put in the muffle furnace after drying. The heat treatment was at 56~64 for 3~12min at a reducing atmosphere (provided by carbon powder), and the heating rate was 5~8 /min. It had been taken out when cooling to room temperature. The glass surface was cleaned with a soft cloth, then the brown glass with smooth surface was obtained. 2.2 Characterization The light transmittance of samples in the visible region was tested by LAMBDA 35 spectrophotometer. The color of sample surface was characterized by dominant wavelength (λ ) and color purity (P), both were calculated from the values of light transmittance according to CIE standard colorimetric system[6-7]. The microstructure of sample surface was observed by Quanta 25 FEG scanning electron microscope (SEM) of FEI Company. The energy dispersive X-ray spectra (EDS) of sample was measured with an energy dispersive spectrometer attached to the scanning electron microscope. 3. Results and discussion 3.1 Influence of coloring ions content on coloring effect The mass of AgNO 3 and CuSO 4 accounting for color paste is denoted by R, the mass ratio of AgNO 3 and CuSO 4 is denoted by r, temperature and time is denoted by T and t, respectively Influence of R on coloring effect In four groups of color paste, the values of R are 5%, 6%, 7% and 8%, respectively, r=1:5, T=62, t=6min. Figure 1 shows the transmittance curves of prepared samples, table 1 is the dominant wavelength and color purity of samples. It can be seen from the transmittance curves in Figure 1 and the dominant wavelength data in Table 1, the dominant wavelength of prepared samples is between 58~6nm, located in the brown area of ligulate chromaticity diagram, and the surface of samples presents brown. The color change of samples is mainly reflected in the long wavelength (>5nm). The light transmittance of samples decreases with the increasing of the mass of silver nitrate and copper sulfate in paste, and the glass color deepen gradually, from 18

3 Journal of Materials and Applications 3:1 (214) % 6% 7% 8% Fig. 1 Light transmittance curves of samples prepared at different R Tab. 1 Dominant wavelength and color purity of samples R/wt% λ /nm P/% tawny to dark brown. When R=7%, the dominant wavelength of samples reaches maximum (598nm), and the color purity is the highest (94.12%). In this condition, samples get the deepest color, and show dark brown. It can be considered that the coloring effect is best when the mass of AgNO 3 and CuSO 4 accounts for 7% of the paste. The sample color becomes shallower when R=8%. It is due to the reduction components in paste decline, which is adverse to the chromogen of coloring ions, when the content of AgNO 3 and CuSO 4 increases Influence of r on coloring effect In three groups of paste, R=7%, the values of r are 1:4, 1:5 and 1:6, respectively, T=6, t=6min. Figure 2 is the transmittance curves of prepared samples, Table 2 is the dominant wavelength and color purity of samples :4 1:5 1: Fig. 2 Light transmittance curves of samples prepared at different r 19

4 3:1 (214) Journal of Materials and Applications Tab. 2 Dominant wavelength and color purity of samples r 1:4 1:5 1:6 λ /nm P/% It can be seen from the light transmittance curves in Figure 2 and the dominant wavelength data in Table 2, the surface of the three sets of samples exhibit brown. The transmittance curves are very close to each other when the values of r are 1:4 and 1:6, and decline significantly when r=1:5, indicating that the color of the former two samples is almost the same, while the color of the latter is much deeper. We can also come to the same conclusion from the values of dominant wavelength and color purity in Table 2. Therefore, When the mass ratio of CuSO 4 and AgNO 3 is 1:5, it can achieve the best coloring effect. The coloring effect would be weakened when the mass ratio of silver nitrate and copper sulfate is too large (1:4) or too small (1:6). It is determined by the composition of high borosilicate glass. First, the sodium ion in high borosilicate glass is little, making it hard for ion exchange reaction. The diffusion of silver ion is much faster than copper ion on the glass surface, and ion exchange reaction for silver ion is also more prone to occur. Second, the reduction components content of high borosilicate glass is in a low level, which is adverse to the chromogen of coloring ions, and the chromogen of silver ion is relatively easier than copper ion. 3.2 Influence of temperature on coloring effect In a paste, R=7%, r=1:5, the values of T are 58, 6, 62 and 64, respectively, t=9min. Figure 3 is the transmittance curves of prepared samples, Table 3 is the dominant wavelength and color purity of samples Fig. 3 Light transmittance curves of samples prepared at different temperatures Tab. 3 Dominant wavelength and color purity of samples T/ λ /nm P/%

5 Journal of Materials and Applications 3:1 (214) It can be seen from the transmittance curves of samples prepared at different temperatures in Figure 3, with temperature rise, the light transmittance of samples does not show a regular change in the wavelength range of 55~65nm. Wherein the samples prepared at 6 and 64 have a similar and higher transmittance, but the transmittance of samples prepared at 58 is relatively low, while the samples prepared at 62 is the lowest. In this situation, the color of samples is the deepest, and show dark brown. From Table 3, samples prepared at 62 get the maximum dominant wavelength (63nm) and the highest color purity (95.71%). Thus, heating treatment at 62 can abtain the best coloring effect. 3.3 Influence of heat preservation time on coloring effect The color paste is the same as 2.2, T=62, the values of t are 3min, 6min, 9min and 12min, respectively. Figure 4 is the transmittance curves of prepared samples, Table 4 is the dominant wavelength and color purity of samples. It can be seen from the transmission curves of samples prepared at different heat preservation time in Figure 4 and the dominant wavelength data in Table 4, the transmission curves of samples show a tendence of gradual decline when the heat insulation time changes from 3min to 9min. The dominant wavelength and color purity increase gradually with the extension of heat treatment time, and reach maximum when insulated for 9min, which are 596nm and 95.17%, respectively. In this situation, the color of samples is the deepest. While continuing to extend heat insulation time to 12min, the light transmittance of samples is almost constant. The dominant wavelength increases little (597nm), while the color purity declines (93.86%), and the samples color does not change significantly. Hence, heating treatment for 9min can achieve ideal coloring effect min 6min 9min 12min Fig. 4 Light transmittance curves of samples prepared at different heat preservation time Tab. 4 Dominant wavelength and color purity of samples t/min λ /nm P/% Influence of atmosphere on coloring effect In a paste, R=7%, r=1:6, T=62, t=9min. One group was heated under a strong reducing atmosphere, while another was in an air atmosphere. Figure 5 is the transmittance curves of prepared samples, Table 5 is the 21

6 3:1 (214) Journal of Materials and Applications dominant wavelength and color purity of samples. 8 7 C Without C Fig. 5 Light transmission curves of samples prepared under different atmospheres Tab. 5 Dominant wavelength and color purity of samples Atmosphere C Without C λ /nm P/% It can be seen from the transmittance curves of samples prepared under different atmospheres in Figure 5, the light transmittance of samples prepared under a strong reducing atmosphere is significantly lower than samples prepared in an air atmosphere. As described above, the reduction reaction of coloring ions is not easy to occur due to the reduction compositions in high borosilicate glass is rare. Therefore, reducing substances (zinc powder and carbon powder) were added in paste and a strong reducing atmosphere was adopted in the process of heat treatment in order to promote the reduction process of coloring ions and improve the coloring effect[8]. Obviously, a reducing atmosphere can largely improve the coloring effect. 3.5 Phase analysis The color paste is the same as 2.2, T=62, t=9min. Figure 6 is the SEM photograph of samples, EDS tested in the circle-marked place, Figure 7 is the EDS energy spectra of samples. It can be seen from the SEM photograph of samples in Figure 6, the sample surface exists colloidal particles (or micelles) in a diameter of about several micrometers to dozens of microns, most present regular spherical, but few irregular strip. The chromogenic mechanism of ion diffusion colouring shows that recrystallization phenomenon occurs when Ag + and Cu 2+ have been reduced to the corresponding metal atom, then the crystallization of Ag and Cu interact and gather into colloidal particles, which further form color base and show brown[9]. It can be seen from the EDS energy spectra of samples in Figure 7, there are Ag and Cu elements existing in the crystal of samples, proving that the coloring ions in paste have had ion exchange reaction with the composition of glass surface followed by reduction reaction. Wherein Ag is yellow, Cu is red, there may be a small amount of Cu 2 O, also show yellow[1]. Three elements Si, O and Al are the composition of high 22

7 Journal of Materials and Applications 3:1 (214) borosilicate glass, while the Au characteristic peaks are caused by the gold film plated on the surface of samples. Fig. 6 SEM photograph of samples 5 4 Au Si O Al Cu Au Ag Cu Au Energy/keV Fig. 7 EDS energy spectra of samples 3.6 Test of hot corrosion resistant performance To test the hot corrosion resistant performance of the color on glass surface, we used an alcohol blowtorch to heat the colored portion of glass locally. It can be seen the brown coloration on glass surface does not have any significant change until the glass starts softening deformation. The color still keeps the same and the colored lines are stable with the increase of temperature, proving the diffusion phenomenon does not occur. It is revealed that the coloration of high borosilicate glass has good hot corrosion resistant performance under the glass softening point (82 ). 4. Conclusions The brown high borosilicate glass with durable and non-shedding color and smooth surface was prepared by diffusion coloration with silver and copper ions. A better coloring effect can be achieved when the mass of AgNO 3 and CuSO 4 accounts for 7% of the color paste, the mass ratio of AgNO 3 and CuSO 4 is 1:5, and heat treatment at 62 for 9min. Meanwhile, heat treatment under a reducing atmosphere can obtain a better coloring effect. Micelles with a diameter of several micrometers to dozens of microns exist on the glass surface, 23

8 3:1 (214) Journal of Materials and Applications which are generated by the interaction of Ag and Cu, most present regular spherical, but few irregular strip. The coloration of glass surface has excellent hot corrosion resistant performance. The color keeps the same and the colored lines are stable. Diffusion phenomenon does not occur until the glass starts softening deformation. References [1] Dexiang Dong, Shuangjing Fan. Research on silver and copper ion diffusion coloring. Science Journal of Teachers, 2, 2(1): [2] Abel Puche-Roig, Vicent Primo Martin, Sonia Murcia-Mascaros, et al. Float glass colouring by ion exchange. Journal of Cultural Heritage, 28, 9: [3] An Yu Zhang, Tatsuga Suetsugu, Koheikadono. Incorporation of silver into soda-lime silicate glass by a classical staining process. Journal of Non-Crystalline Solids, 27, 353(1): [4] Yanxing Wang, Chengkui Zu, Jiang Chen. Influence of composition on viscosity and expansion coefficient of high borosilicate glass. Functional materials, 212, 43(21): [5] Junpeng Wan, Jinshu Cheng, Liying Tang. Introduction of application status and development trend of borosilicate glass. Glass, 24, 5: [6] Fu Chen, Lihua Wu, Enlu Zhao. Introduction to color glass. Chemical industry press, 29. [7] Yanzhao Zhao, Hairong Yin. Glass technology. Chemical industry press, 26. [8] Xiaoming Wang. Ion diffusion coloring of flat glass surface. Glass, 1989,5: [9] Peter Grego, Theodore R. Kozlowski, Peter M. Schuyler. Decorating glass-ceramic articles. U. S. Patent 3,65,72, [1] Hua Chen, Yiming Ying, Jindong Chen. Several issues of copper ion diffusion coloring on glass surface. Glass, 1987, 1: