Wettability of ferromagnetic powders of the Fe-Co-Ni system by organic solvents

Abstract

Quantitative data on the wettability of the surface of particles of thermochemically prepared ferromagntic powders have been obtained for the first time. It is established that their wettability can be enhanced by the introduction of surfactant substances. This makes it possible to create different nanostructured materials, for example, glues and sealants in which nanocomposite ferromagnetics serve as fillers. These materials are used to seal cracks, and eliminate defects in active main gas pipelines operating under extreme conditions.Information on the character of component interaction is required where ferromagnetic powders are used as fillers for the development of various nanostructured sealing compounds, for example, glues and sealants. Familiar composites do not fully satisfy material requirements for the sealing of cracks, blowholes, and other defects in active main gas lines operating under extreme conditions. In many cases, different liquids that may affect the surface properties of ferromagnetic powders are used as the disperse medium in the development of different composites.The purpose of the present study is to investigate the wettability of ferromagnetic powders that we have used as fillers in developing glues and sealants for service under extreme conditions. Nanocomposite Fe powders and powders containing 60 mass% of Fe, 30 mass% of Co, and 10 mass% of Ni were prepared by thermochemical means [1]. The powders have particle sizes ranging from 0.06 to 0.1 μm, and a specific surface of 20-28 m 2 /g. The surface of the powder particles is hydrophilic, and the particles are corrosion resistant, nonpyrophoric, and endure heating temperatures to 100 ± 10°C.The magnetic characteristics of the iron powders are: a coercive force H c = 24-32 kA/m, a specific saturation induction σ s = 100-120 A ⋅ m 2 /kg, a specific residual induction σ r = 22-28 A ⋅ m 2 /kg, and a coefficient of relative residual induction K = 0.2-0.25. The magnetic characteristics of the iron − cobalt − nickel powders are: H c = 49-60 kA/m, σ s = 180-200 A ⋅ m 2 /kg, σ r = 70-80 A ⋅ m 2 /kg, and K = 0.4-0.45. The phase composition of the iron powders, mass%, was established by methods of NGR-spectroscopy and x-ray phase analysis: 50-60 of Fe met , 25-30 of Fe 3 C, 14-19 of Fe 3 O 4 , and 0.7-1 of free C. Powders of the iron − cobalt − nickel system contained the following, mass%: 65-70 of the metals, 18-20 of Fe 3 C, 12-14 of Fe 3 O 4 , and 1-1.2 of free C. The surface of the powders is protected by the oxides of iron and its carbide.The heat of wetting Q of the iron and Fe − Co − Ni powders by different solvents was determined using an Setaram-made Calvier microcalorimeter in accordance with the familiar procedure outlined in [2]. Selection of solvents was dictated by their continued use for the development of nanostructured materials. The surface of the particles of the ferromagnetic powders is hydrophilic.