AVS 49th International Symposium
    Surface Engineering Tuesday Sessions
       Session SE+TF-TuA

Paper SE+TF-TuA9
Rheological Behaviour of Alumina-Diamonds-Polymer NanoComposite Structure

Tuesday, November 5, 2002, 4:40 pm, Room C-111B

Session: Systems Design of Functional Coatings
Presenter: I.A. Nemerenco, NAMATEX System Division, Institute of Machine Reliability, Russia
Authors: I.A. Nemerenco, NAMATEX System Division, Institute of Machine Reliability, Russia
M.V. Kireitseu, NAMATEX System Division, Institute of Machine Reliability, Russia
L.V. Yerakhavets, NAMATEX System Division, Institute of Machine Reliability, Russia
Correspondent: Click to Email
To predict strength and deformation of the alumina-diamonds-polymer nanocomposition under Hertzian indentation the rheological model has been developed. The model is based on combined simple rheological elements that in general gives accurate results in comparison with one obtained in Hertzian indentation technique. Based upon the investigations we have suggested the following requirements to be used in rheological model of the nanocomposite structure: 1. Since the composite include hard alumina layer and steel substrate that exhibit plasticity, the irreversible deformations has to be considered as plastic in nature. Deformations develop only after excess of some critical yield strength for the particular layer of the composite. 2. if the deformations are smaller then yield strength, the deformations at constant stress have to grow up step-by-step to final value; 3. Cyclic loading increases summarized plastic deformation of the composite; 4. Curve of deformation vs. time at constant load exhibits a linear dependence in one of plotted region. 5. At unloading the retardation of deformations (elastic return) has to be observed; 6. Stress at constant deformations is relaxed. The selection of model that adequate to the studied composite material is determined by comparison of developed models and experimental results. The composite of hard alumina-diamonds-aluminum can be presented as elastic-tenacious-plastic rheological model of the composite. The mechanical prototype of the model is described in a book. Structural equations of the integral model of the composite looks like (H || N || St-V) - (H-N || H). In general, the kind of the rheological equation depends on a level and form of stress applied on model. The polymer layer can be presented as the rheological model consisting from two elastic elements and one tenacious element. As a prototype of the model, we can consider connection of the Maxwells' model and elastic element. The composite exhibits linear relation of stress curve, whereas unloaded composite shows retardation of deformations (elastic return) shown as downfall segment of the curve. The plotted relations of experimental data and calculated data have revealed very close agreement of developed rheological model and real mechanical behavior of the composite. The above stated conditions are found to be used in investigations of mechanical and rheological properties of the alumina-aluminum-polymer-steel composite systems. The rheological properties and perspectives to be considered in development of such nanocomposite structure have been discussed.