RU2461087C1 - Fluid composition having magnetorheological properties - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: fluid composition having magnetorheological properties contains diamond nanoparticles as an abrasive. Processing optical components using diamond nanoparticles as the abrasive improves surface quality.

EFFECT: invention enables to maintain for the disclosed fluid composition, a life span of 15 days, sedimentation resistance, magnetic field sensitivity, reduce initial viscosity and improve processing characteristics of optical components.

1 tbl, 4 ex

Description

The invention relates to compositions of fluid compositions that respond to the action of a magnetic field by a sharp change in their rheological properties, and can find application in mechanical engineering, robotics, for controlling the flow of a working fluid in hydraulic devices (dampers, vibrators, drives, etc.), instrumentation, in particular, for finishing optical surfaces in a magnetic field.

The use of magnetorheological fluid as a polishing material can significantly improve the surface quality of optical parts and increase processing productivity. Since the polishing material is formed by a magnetic field in the processing zone, the labor costs for its manufacture are significantly reduced (the manufacturing technology of magnetorheological liquid is simple compared to the production of solid resin polishing forms). When polishing using magnetorheological polishing material, the polished part sets its shape, therefore there are no restrictions on the shape of the surface being treated and it becomes possible to process complex aspherical surfaces.

A known composition for structure-reversible polishing tools for processing optical glass [1], containing, wt.%:

polite 11.7-17.45 carbonyl iron 27.9-56.12 vinyl H-butyl ether polymer 0.96-1.83 α-naphthol 0.0064-0.013 kerosene 12.33-23.63 dodecyl sulfonic acid sodium salt 0,033-0,05 aerosil 2.34-4.49 water rest

This composition due to the use of polite as an abrasive allowed to intensify the processing of optical parts.

However, the presence of kerosene and water in the composition does not allow to obtain a homogeneous mixture.

Known magnetorheological fluid composition based on water [2], containing, vol.%:

carbonyl iron particles 36.05 cerium oxide 5.7 glycerol 2,4 sodium carbonate 0.74 water rest

The formulation of this fluid was developed on the basis of conditions for ensuring the ablation rate of the processed material (2-3) μ / min, which is an order of magnitude higher than when using previously known polishing pad, and allows to obtain a final surface roughness of 10 Å.

However, the practice of operating a magnetorheological liquid of the above composition under conditions of constant circulation and mixing in contact with air has shown that at a certain stage there arises a “lifetime” problem associated with irreversible changes (corrosion) of carbonyl iron particles upon contact of their surface with water. In addition, the formation of oxides and hydroxides on the particle surface arbitrarily changes the conditions at the solid – liquid interface, which, in turn, affects the rheological properties of magnetorheological liquids and the quality of surface treatment of the optical part [3].

Known fluid composition with magnetorheological properties [4] (protopip), in which in order to increase the "lifetime" or, otherwise, the working time introduced an additional component - sodium hexametaphosphate. Such a liquid contains, vol.%:

carbonyl iron particles 36.05 cerium oxide 5.7 glycerol 2,4 sodium carbonate 0.74 sodium hexametaphosphate 0.01-0.1 water rest

This composition allowed to increase the "life time" of magnetorheological fluid from 5 to 15 days.

Modern requirements for optical products provide for a better machined surface, i.e. the root mean square surface roughness should be less than 10 Å.

The objective of the present invention is to improve the quality of the processed surface by achieving values of the root mean square micro roughness of 2-5 Å.

The problem is solved as follows. In the known fluid composition with magnetorheological properties containing carbonyl iron particles, glycerin, sodium carbonate, sodium hexametaphosphate and water, according to the invention, nanosized diamond particles are used as an abrasive in the following ratio of components, vol.%:

carbonyl iron particles 36.05 diamond particles 0.001-0.03 glycerol 2,4 sodium carbonate 0.74 sodium hexametaphosphate 0.01-0.10 water rest

The use of nanosized diamond particles as an abrasive instead of cerium oxide will improve the quality of the treated surface and achieve a microroughness of 2-5 Å.

The proposed fluid composition is prepared as follows. In accordance with the formulation, glycerol, sodium carbonate, sodium hexametaphosphate are added to distilled water and stirred until the components are completely dissolved. Samples of carbonyl iron and abrasive powders (diamond particles) are added to the resulting solution (water base). Mix thoroughly for 2 hours until a homogeneous composition is obtained.

In the examples below, various compositions of the claimed fluid composition are considered, and the table shows the comparative characteristics of their properties, since in addition to the main indicator of their suitability - the quality of the processed surface of the optical part, they, from the point of view of working capacity, have mandatory requirements for sedimentation stability; low viscosity outside the field to provide the necessary hydraulic conditions for fluid movement; the stability of rheological properties over time and the absence of agglomerates from particles of a dispersed phase clogging the hydrochannel; the value of the shear stress of a shear in a magnetic field within specified limits.

Sample 1 (prototype). The ratio of the components is the following, vol.%:

carbonyl iron particles 36.05 cerium oxide particles 5.70 glycerol 2.40 sodium carbonate 0.74 sodium hexametaphosphate 0.01-0.10 water rest

Sample 2. The ratio of the components is the following, vol.%:

carbonyl iron particles 36.05 diamond particles 0.001 glycerol 2.40 sodium carbonate 0.74 sodium hexametaphosphate 0.06 water rest

Sample 3. The ratio of the components is the following, vol.%:

carbonyl iron particles 36.05 diamond particles 0.01 glycerol 2.40 sodium carbonate 0.74 sodium hexametaphosphate 0.06 water rest

Sample 4. The ratio of the components is the following, vol.%:

carbonyl iron particles 36.05 diamond particles 0,03 glycerol 2.40 sodium carbonate 0.74 sodium hexametaphosphate 0.10 water rest

In the experiment, carbonyl iron of the P-10 grade (Russia) was used, abrasive was cerium oxide (USA), nanosized diamond powder (USA, Strans Chemical Corporation, I1).

Measurements of the initial (without exposure to a magnetic field) viscosity of the magnetorheological fluid were carried out on a viscometer. The sedimentation constant of liquids placed in a measuring tube was estimated by the sedimentation rate of iron particles. The microroughness of the processed surface of the optical parts was determined using an NT-206 atomic force microscope. The measurement results are shown in the table.

Table Indicator Sample 1 Sample 2 Sample 3 Sample 4 Viscosity without field η, Pa · s, γ = 800 s ^-1 0.21 0.11 0.11 0.11 Magnetic field voltage B = 300 mT τ, KPa 25.1 25.0 25.0 25.1 Sedimentation constant S, MSB 0.06 0.06 0.06 0.06 RMS roughness Rg, Å. 9.7 2.7 2,3 2.5

Thus, as shown by the measurement results, the present invention allows you to save for the proposed magnetorheological fluid indicators as in the prototype - "lifetime" - 15 days, sedimentation stability, sensitivity to the magnetic field and, in addition, to achieve an improvement in the processing of optical parts by 4 times and further reduce the initial viscosity by 2 times. A decrease in the amount of diamond powder (<0.001 vol.%) Affects the quality of the polished surface. An increase in the concentration of diamond powder is impractical because there is no decrease in the surface roughness of the optical part, but the cost of the magnetorheological fluid increases.

Information sources

1. A.S. USSR No. 2034693, IPC B24D 3/34, publ. 1995 year

2. US Patent No. 5804095, IPC B24B 31/00, publ. 1996 year

3. Matsepuro A.D., Novikova Z.A., Gorodkin S.R., Kordonsky V.I. Stabilization of water magnetorheological liquids // Heat and Mass Transfer - 98/99. Minsk, ANK "ITMO them. A.V. Lykova ”, NASB, 1999, pp. 72-76.

4. Patent BY 11595, IPC H01F 1/44, 2007 (prototype).

Claims (1)

Fluid composition with magnetorheological properties containing particles of carbonyl iron, glycerin, sodium carbonate, sodium hexametaphosphate and water, characterized in that it contains nanosized diamond particles as an abrasive in the following ratio of components, vol.%:
carbonyl iron particles 36.05 diamond particles 0.001-0.03 glycerol 2,4 sodium carbonate 0.74 sodium hexametaphosphate 0.01-0.10 water rest