Tribological Analysis of Mg₂Si Particulates Reinforced Powder Metallurgy Magnesium Alloy Composites under Oil Lubrication Condition

Abstract

Recommended by Ming-Xing ZhangFor the evaluation of wear behavior of Mg composites under oil lubrication conditions, powder metallurgy Mg 97 Y 2 Zn 1 alloy reinforced with additive Mg 2 Si particles were fabricated by the repeated plastic working (RPW) and hot extrusion. The RPW process was effective in refining both Mg 2 Si reinforcements and α-Mg grains causing the matrix hardening. When increasing the repetition number of RPW process from 200 to 600 cycles, the particle size of Mg 2 Si additives changed from 8 μm to 1∼2 μm, and α-Mg grain size was 1 μm or less. With regard to the defensive and offensive properties of Mg alloys reinforced with Mg 2 Si dispersoids, the composite had superior adhesive wear resistance compared with the conventional Mg alloys because of its extremely high microhardness of 95∼180 Hv by RPW process. The uniform distribution of refined Mg 2 Si particles was useful for improving both defensive and offensive properties against AZ31B counter disk specimens. The Mg 2 Si prominent dispersoids in the matrix were also effective in forming the oil grooves around them, and caused the low and stable friction coefficient. On the other hand, in the case of the composite containing coarse Mg 2 Si particles, severely deep scratches were given on the counter face of the AZ31B disk, and resulted in an unstable and high friction coefficient.

Manufacture of Locally Reinforced Composite Discs by Casting in the Alternating Electromagnetic Field

“…For this type of materials, the available techniques of manufacturing products with variable spatial distribution of properties include, beside the relatively complex multistage methods of powder metallurgy [11,12] and preform infiltration [3,4], the casting methods where the migration of reinforcement particles in a molten matrix is obtained as a result of various physical forces such as the gravitational force [13] and the centrifugal force [14]. The nonuniform distribution of the reinforcement obtained through particles separation yields the required spatial change of the cast properties.…”

Synthesis and Characterization of Nickel-Alumina Composites from Recycled Nickel Powder

“…The valorization of materials recovered from scrap (metallic waste), a low-price secondary material, into value-added composites, represents a challenge with important technological, economic, and environmental aspects. Metalceramic composites, in particular, often exhibit improved properties with respect to their corresponding monolithic counterparts [1][2][3][4][5][6][7]. The development of such upgraded composites starting from materials recycled from metallic waste may be of particular interest, because of the possibility to reduce the production cost while also responding to environmental demands that are nowadays imposed by the decrease of ore deposits as well as by problems caused by waste rejection.…”