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CHARACTERISATION OF DISPERSIONS FOR PROCESS CONTROL IN THE PRODUCTION OF PARTICULATE MAGNETIC MEDIA

Objective


Many experimental techniques were evaluated. Of particular value have proven the methods of magnetometry in a shear field, analytical filtration techniques and the behaviour of the dispersions at short time scales in a newly developed pulse field magnetometer.

Concurrently with the experimental work a numerical simulation was developed with which to interpret the laboratory data and to become a design tool of media processing and development. Two separate models were developed. The first used Monte-Carlo techniques to generate equilibrium configurations of the particles taking into account magnetic and surface interactions. It became clear from both the simulations and the parallel experiments that complex time effects play an important role in the behaviour of the dispersions and true equilibrium situations may be difficult to find and may in fact not occur in real systems. The second model therefore adopted the molecular dynamics approach while taking over much of the framework of the Monte-Carlo calculation. With the molecular dynamic simulation good agreement has been achieved between the measured and calculated macroscopic magnetic properties of advanced metal particle dispersions. After incorporating a simulated 'drying' stage the model can now generate numerical model of recording tape as the basis for fundamental recording theory.
A crucial intermediate in the production of magnetic recording media is the dispersion that contains the magnetic particles. At present, no scientifically based techniques exist for the characterization of these dispersions. Consequently the process control in the production of current products, as well as the development of new products rely mainly on tests of the final product, the tape. The resulting long delay causes serious production losses and makes development tedious. In view of the increasing requirements in information storage density for High Definition TeleVision, Digital Compact Cassettes, etc. this is an alarming situation.

The proposed project is aimed at new methods for process control in the prouction of the dispersions. These methods will be applicable preferably in-line, and provide insight in the microstructure of the dispersions rather than empirical numbers. A thorough study of the microstructure of selected dispersions by new and advanced techniques as well as by established methods will be followed by the selection and further development of those methods suitable for practical application in process control and product development. the project is of strategic importance for the European media industry because of the strong competition from overseas.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

BASF AG
Address

67056 Ludwigshafen
Germany

Participants (3)

PD MAGNETICS BV
Netherlands
Address
Molenstraat 37 Po Box 82
4900 AB Oosterhout
University of Keele
United Kingdom
Address

ST5 5BG Keele - Staffordshire
University of Wales, Bangor
United Kingdom
Address
Dean Street
LL571UT Bangor