DD241083B1 - POLISHING MIXTURES WITH CEROXIDE FOR POLISHING MATERIALS - Google Patents

Abstract

The invention relates to polish mixtures with cerium oxide and SiO ,. The aim of the invention is to produce polish mixtures which achieve a processing result of high accuracy, cleanliness and effectiveness in accordance with the respective requirements and matched to the glass, crystal or ceramic material to be processed or a group of these materials. The object is achieved in that mixtures of cerium oxide and silicon xerogel are produced. The exact mixing ratio depends on the demands placed on the material surface and the type of material. The polish mixtures may be suspended in a liquid or used in bonded form for polishing.

Description

embodiments

To prepare a polish mixture according to the invention for producing an optical component made of boron-crown glass, 69% by mass of cerium oxide and 31% by weight of xerogel are mixed in finely divided form. Subsequently, the mixture is suspended in water until a density of the suspension of 1.1 like " ³ sets

 On the polished optical component with the mixture according to the invention is a stray light after polishing

S measured from --- the scattered light initial value. For the component, polished with a suspension containing only cerium oxide, a scattered light value S of - the scattered light initial value is measured after the same polishing time.

To achieve the desired scattered end value S of must with the only ceria-containing polishing suspension the

2.5 times the polishing time compared to the polishing time required with the mixture according to the invention. Other embodiments of glass, crystal and ceramic are shown in the table. The roughness depth R _m is used as the comparison value for ceramic and the mean square deviation rms for the crystal.

Auüführungsbeispiele

material

mech. Characteristic size / unit

Polish mixture,

processing result

needed iolierzeit

BK7

BK7

Glass

sin

SP 3

relative grinding hardness according to glass catalog

ceria

00 100 Ma. -% ü = 2 3 · ίο - 15 mm 1, 49 Cerium oxide / xerogel 69 Ма - '/ о / З! Ma. -% S = 4 , 0 · 1C " ⁴ 15 min O, Geroxide 100 Ma. -% S = 1 , ο ю- ¹ 20 min

Geroxide / Xerogel 73% by mass / 27% by mass

S = 6.9 * 10

-4

20 min

JEIIIT

JElTIT R 40 print Kera mik ilmavit R 40 firmness ilrnavit TGL 9409 quartz Kri Hardness after barn IvIOHS

Nmm

-2

-2

Geroxide 100 Ma. -%

R = 0.34 / um

Geroxide / Xerogel 69 Ma.-fc / 31 Ma.-J

= 1.37 / um

12 min

450 Itfmm Cerium oxide / xerogel 69% by mass / 31% by mass ^R m = 0 , 15 / Um 12 rain 243 Nmm Cerium oxide 100% by mass 2 , 80 / um 3 min

3 min

Cerium oxide 100% by mass

m8 = 1.8 nm

quartz

Cerium oxide / xerogel 65% by mass / 35 Ma.-JI

rms = 1.2 nm

20 min

20 min

Claims (1)

Polishing agent mixture for the polishing of glass, crystal and ceramic surfaces, consisting of cerium oxide and SiO ₂ , characterized in that for the Si0 ₂ components silicon xerogel as an already known mixture of 90 to 99.9Ma .-% silica gel and 0.1 to 10 Ma .-% non-porous silica with two resulting pore systems is used, the pore systems as a pore system 1 with a mean pore radius r _Pf1 = 3 to 5nm at a frequency of r _p1 as φ = 0.05 to 0.1 OnrrT ¹ and as _Pore system 2 with an average pore radius r _Pr2 = 5 to 8nm at a frequency of r _p2 as φ = 0.30 to 0.50 nm ~ ^{1 are} characterized and the mixture has a BET specific surface area of 200 to 600m ² / g and a Total pore volume of at least 0.7 cm ³ / g has. Field of application of the invention The invention relates to the composition of polish mixtures with ceria and SiO ₂ for polishing glass, crystal and ceramic surfaces. Applicable are the polish mixtures in suspended or bound form. Characteristic of the known technical solutions Ceria is a known and effective but costly polish. It can be seen from some sources that the effect of polishing agents, as well as cerium oxide, can be improved by additives. The CH-PS 612990 describes an improvement in the operating properties of a diamond paste by the addition of 5Ma .-% silica. DE-AS 1239044 indicates that the effectiveness of polishing agent blends is increased when certain dioxides and monoxides are mixed. According to GB-PS 1160126, the efficiency of the cerium oxide polishing agent can be increased by a proportion of 0.5 to 20% by mass of silicon dioxide in the total mixture. Preferably, a mixture of 4 to 5% by mass of silica is used in the total mixture. Already mixtures with up to 8Ma .-% silica are referred to as no longer attractive because the silica is attributed to the polishing of glass or glass-like materials only a very lower polishing effect (DE-AS 1266426). Furthermore, from DD-PS 216477 a polish mixture of cerium oxide and other rare earths with hydrated silica is known whose particle diameter is 2-60 μιτι and in the ratio of 5-95%, preferably 50%, is added. The purpose of this mixture is to increase the availability of the polishing agent in the feed unit by preventing settling. Of significant disadvantage is that hydrated silica is not applicable as additive to cerium oxide in the entire material range (glass) for precision polishing, since the required surface quality (scattered light) is not reached. All described polish mixtures require additional proportions of other substances (for example monoxides and dioxides) in order to increase the polishing performance, are limited in the quantity of admixture of these components or do not achieve the required surface quality. Object of the invention The aim of the invention is to find polish mixtures, in particular for the production of optical functional surfaces, which achieve the respective respective requirements and, matched to the material to be processed, a processing result of high accuracy, cleanliness and effectiveness. The degree of smoothening of the surface should be equal to or better than that possible with cerium oxide without additives, and the polish mixture must be reproducible. Explanation of the essence of the invention The invention has for its object to find polish mixtures that achieve a high accuracy of the surface while maintaining or improving productivity. According to the invention the object is achieved in that mixtures of cerium oxide are prepared with silicon xerogel, in which the silicon xerogel as an already known mixture of 90 to 99.9Ma .-% silica gel and 0.1 to 10Ma .-% non-porous silica with two resulting Pore systems present as pore system 1 with a mean pore radius r _p2 = 3 to 5nm at a frequency of r _p1 as φ = 0.05 to О.ЮпггГ ¹ and pore system 2 with a mean pore radius r _p , ₂ = 5 bis8nm at a Frequency of r _{Pi2 are characterized} as <p = 0.30 to 0.50 nm ~ ¹ , wherein the mixture has a BET specific surface area of 200 to 600m ² / g and a total pore volume of at least 0.7cm ³ / g. The exact mixing ratio depends on the demands placed on the material surface and the type of material. It is determined according to the methods of statistical experimental design known in the art. By varying the constituents cerium oxide and xerogel in the mixture, optimally matched polish mixtures can be prepared with regard to the speed of separation and smoothing, the cleanliness and accuracy for certain materials or material groups. The advantages of the polish mixtures lie in a shortening of the necessary polishing times with the same or better smoothing, cleanliness and accuracy of the material surface to cerium oxide without additives. Costly ceria can be partially replaced by xerogel. Up to 50% cerium oxide savings are thus made possible.