Hardness and friction behavior of bulk CoAl2O4 and Co–Al2O3 composite layers formed during Spark Plasma Sintering of CoAl2O4 powders

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. powders. The Co particles are precipitated because of a combination of high temperature and low O 2 partial pressure. The precipitation and densification processes hamper each other and thus the way the uniaxial pressure is applied during the sintering cycle is an important parameter to control the microstructure of composite layer and its thickness (about 100 mm) and obtain a dense sample (about 4 g/cm 3 ). The friction coefficient of the CoAl 2 O 3 composites against an Al 2 O 3 ball is lower than that found for an Al 2 O 3 specimen, which could reveal the lubricating role of submicrometer Co particles. However, increasing the load from 5 to 10 N load causes major changes in the friction contact, which are detrimental. Bulk CoAl 2 O 4 was found to have a Vickers microhardness about 15.5 GPa and an average friction coefficient lower than that of an Al 2 O 3 sample.

Nanomechanical Filler Functionality Enables Ultralow Wear Polytetrafluoroethylene Composites

“…The elastic modulus and hardness of alumina were taken to be 392 GPa and 19.25 GPa, respectively, which correspond to a γ value of 0.79. Similarly, the modulus and hardness of cobalt aluminate were 256.8 GPa and 15.5 GPA, respectively, which result in a γ value of 0.75 . A graphic overview of the nanoindentation experiments is shown in Figures and .…”

“…Similarly, the modulus and hardness of cobalt aluminate were 256.8 GPa and 15.5 GPA, respectively, which result in a γ value of 0.75. 50 A graphic overview of the nanoindentation experiments is shown in Figures 1 and 2.…”

The Influence of Co Additive on the Sintering, Mechanical Properties, Cytocompatibility, and Digital Light Processing Based Stereolithography of 3Y-TZP-5Al2O3 Ceramics

“…The cobalt addition resulted in a significant increase of the microhardness up to 8.3 ± 0.2 GPa for 1350 • C and 10.3 ± 0.2 GPa for 1450 • C for composition II. The increase of Co additive amount resulted in the considerable increase of the microhardness up to 11.6 ± 0.2 GPa for composition III at 1450 • C linked with the formation of spinel CoAl 2 O 4 grains according to SEM, which characterized by higher microhardness comparing to t-ZrO 2 (Figure 4) [44]. Composition IV was characterized by 10.6 ± 0.2 GPa at 1450 • C due to the simultaneous formation of CoAl 2 O 4 and a coarse-grained structure based on the high amount of the m-ZrO 2 [45].…”

A comparative study on citrate sol‐gel and combustion synthesis methods of CoAl2O4 spinel

“…Aluminates are chemicals made up of ceramic materials based on aluminum oxide as the main constituent. Aluminate materials are widely used in high‐technology applications due to their unique properties, for instance, in magnetic materials, ceramic catalysis, absorbent materials, and so forth 1‐4 …”

“…Nowadays, cobalt aluminate (CoAl 2 O 4 ) are used as a color pigment in digital ceramic printing, cobalt and gibbsite precursor, catalyst, and color filter 1‐6 . Moreover, this kind of spinel is one of the great interests among spinels due to its significant properties such as thermal and chemical stability, 6 optical host matrix, 4 high ability of cation diffusion, 4‐7 catalytic application, to name but four 8‐10 …”