Strengthening Process And Mechanism Of Optical Glass

Optical glass is one of the important optical materials, and it's widely used in modern agriculture and industry, national defense, scientific research, cultural life, etc. With the fast development of science and technology, optical glass should meet higher requirements. It should have special and widely optical constants to simplify and improve the design of optical system,and need to have specific physicochemical properties to satisfy a particular purpose. This paper researched on the strengthening process of the K9 optical glass. This process used heat treatment, acid etching, ion exchange to strengthened optical glass, and strengthened again the sample which can not get a well effect. It can save material and reduce cost. Using metallographic microscope to observed the change of the scratches at the optical glass's surface. Through the point scanning by SEM, researched the content and distribution of elements at the surface of glass, researched the effect of Na+ and K+ ion exchange, and then tested the thickness of ion exchange layer. Finally tested the flexural strength of glass samples by three-point bending experiment to measure effect of strengthening process. This paper includes the following main results:1) The optimal parameters for heat treatment strengthening process of optical glass is heat treatment at 580℃for 5 hours. After heat treatment.After heat treatment strengthening, the flexural strength of glass will increased by 20%. Before and after heat treatment, through metallographic microscope to observed the change of the scratches at the optical glass's surface, we can also found that scratches become thinner and shallower. According to the mechanics theory, this change will contribute to strengthening the optical glass, the result of three point bending test is also prove it.2) The optimal parameters for acid corrosion strengthening process is 4%HF+7%H2SO4 for 50min. Under this process, the strengthening effect of acid corrosion is best, the average corrosion rate is 0.9148μm/min.The three-points bending strength of the glass samples after acid corrosion will increased by 30%. Before and after the acid corrosion, the surfaced nicks' morphology of the optical glass sample changed obviously, and the results of the three-points bending test also verified the analysis.3) According to the line scanning and the point scanning energy spectrum analysis, after 458℃for 18h chemical enhancement,the ion exchange layer's depth of the optical glass surface can reach 70μm. The content of K+in the optical glass surface can reached 8%～9%, and increased by 50% in contrast to the original glass. And the optical glass surface will have a high-density area of K+, the depth of it is 60μm.4) Use the chemically strengthening process can greatly improved the flexural strength of optical glass. The flexural strength of optical glass will more than 370MPa, at least fourfold than the original glass. Using acid etching before chemically strengthen process, flexural strength can reached 420MPa.5) Use comprehensive strengthening measures,K9 optical glass's flexural strength can reached 470Mpa. It's fivefold more than the original glass. The flexural strength of Optical glass in this paper there are very few people can do.