Chemical strengthening

Aluminosilicate glasses are used commercially because they can be chemically strengthened and withstand high temperatures. Thus apphcations include airplane windows, frangible containers, lamp envelopes, and flat panel display devices. 

Fig. 7. Cross section of Sierracin windshield used on Boeing 747 (32) A, 2.2-mm chemically strengthened glass B, Sierracote 3 conductive coating C, 1.9-mm PVB D, 23-mm stretched acryflc E, 1.3-mm PVB F, laminated cloth spacer ring G, 23-mm stretched acryflc H, 0.6-mm PVB and I, 3.0-mm...

Chemical strengthening, 13 498-499 Chemical structures, of amino acids,... 

FIG. 117. Stress distribution in a sheet of toughened (dashed line) and chemically strengthened (full line) glass. 

Chemical durability of glass, 186-189 Chemical strengthening, 175—176 China, 302,311... 

Strong and Shatter-Resistant Glasses 17.3.2.4.2. Chemical Strengthening. 

Other methods of chemically strengthening glass include Li ions diffused into a sodium-containing glass to create a composition profile in which the resulting surface has a lower expansion than the core region, and thus develops a compressive layer on... 

Major disadvantages of chemical strengthening by ion exchange include costs, (in time and materials). In addition, not all compositions may be strengthened to useful depth profiles and the temperature used permits stress release by continued diffusion of alkali or structural relaxation of the network. 

G. A. Chase, T.R. Kozlowski and R.P. Krause, Chemical strengthening of ophthalmic lenses, Am. J. Optom., 50 (1973) 470 and Suresh T. Gulati, Frangibility of Tempered Soda-Lime Glass Sheet, Proc. Glass Processing Days, Tampere, Finland 1997, p. 72,... 

The ion exchange or chemical strengthening of glass was almost abandoned for many years because of the high processing cost and long-duration process. In recent years, this method has been reconsidered because of the possibility of mechanical treatment after strengthening, the applicability to complicated shape and limited thickness components, and the absence of optical distortion [8]. 

A semi-automatic chemical strengthening lab scale furnace was used for the ion-exchange treatment. In each run, 20 samples were placed in a stainless steel basket to be treated at 450 °C for 4 h, with 30 min preheating and 30 min post-cooling above the bath. At least 60 samples were treated in each bath with the same thermal and time condihons. 

Varshneya AK, Spinelli IM. High-strength, large-case-depth chemically strengthened lithium aluminosilicate glass. American Ceramic Society Bulletin, 2009 88(5) 27-32. 

Hardness and toughness of chemically strengthened dental porcelains... 

In this section, the effects of chemical strengthening using ion exchange by paste method on the hardness and fracture toughness of dental porcelains with different microstmctures are shown. Table 1 shows descriptions of five porcelain powders used in this study, two recommended to be used as veneering materials for alumina cores (V and Ob) and three recommended for porcelain fused-to-metal restorations (C, D, and B), containing wide variation of leucite fraction (0 to 22 vol%). 

Varshneya AK. Chemical strengthening of glass lessons learned and yet to be learned. International Journal of Applied Glass Science 2010 1(2) 131-142. 

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