Studies concerning the optimization of ceramic magnets anisotrope pressing M. Mangra, M. Ivanescu, V. Stoian, O. Gingu * University of Craiova, 13 A.I. Cuza Street, 1100 Craiova, Romania Abstract This paper presents some research results concerning the optimization of the wet anisotrope pressing of Ba and Sr ferrite powders. The increasing of the structural anisotropy degree ± K ± of the permanent ceramic magnets by the addition of some surfactants to the liquid of the pressing slurries is the main purpose of this research. Also, there is an exploration of the optimization effects on the anisotrope pressing forming operation from the point of view of the relationship between the microstructural anisotropy degree ± K ± and the energy improvement ± BH max ± of the manufactured magnets. # 1999 Elsevier Science S.A. All rights reserved. Keywords: Ba ferrite powders; Permanent ceramic magnets; Anisotrope pressing; Filling volume; Structural anisotropy degree; Speci®c magnetic energy 1. General considerations The ®lling volume V is an in¯uencing factor on the humid anisotrope pressing in a magnetic ®eld of ceramic magnetic powders because it determines the product density, and also strongly in¯uences the orientation degree of the particle powders along the external orientation magnetic ®eld lines, as can be seen in Fig. 1. It is noted that for the products having a particular type of con®guration such as ring magnets ± the radial orientation, which is the best one, could be obtained for a reduced ®lling volume V . Many technical papers have analyzed this aspect and have proposed different solutions in order to control the V para- meter [1±4]. From all of these papers, very good results were mentioned by the researches when increasing the solid content C of the pressing slurry by surfactants addition to the liquid slurry [5,6]. In this case it is necessary to consider a new parameter which is the pressing working temperature, T . This choice is explained by the results of experiments, which have been demonstrated that in the temperature range (0±50)8C there could be obtained repeatability in the para- meters. For these reasons, the implication of the thermal variation versus the structural and functional characteristics of the magnets has been studied. 2. Experiments For the experiments the addition of solutions of lignine and Ba hexaferrite powder was studied [6]. The research program has the following phases: Journal of Materials Processing Technology 89±90 (1999) 481±483 *Corresponding author. E-mail: rector@alpha.comp_craiova.ro Fig. 1. Particle powder orientation. 0924-0136/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved. PII:S0924-0136(99)00130-2