Debris, formation

Fractionation correlation techniques have been applied to cloud, fallout, and ground-filter samples from the Transient Nuclear Test of January 1965. Although safety analysts do not consider fractionation effects to be of operational importance for this type of event, analysis of such data provides insight into the mechanisms of debris formation. The results show many similarities to the correlations observed for fallout. Those dissimilarities found indicate the importance of escape processes to the formation mechanisms for this type of debris. 

Fig. 7. 13 Differences in crack wake contact and bridging mechanisms seen between static and cyclic fracture in AD 90 alumina at 1050°C. From Ref. 34. (a) Deflected crack path during static crack growth with no debris formation, (b) Deflected crack path with debris particles formed at a result of repeated rubbing between the crack faces under cyclic loading. Also seen are the debris and glass films which are squeezed out of the crack due to the pumping action of the crack walls.

Surface treatments of carbon fibers include oxidative treatments. This results in cleaning of the surface impurities and debris, formation of chemical surface groups (largely acidic) at the carbon fiber surface and a rougher surface morphology, all of which result in enhanced mechanical interlocking with the polymeric matrix. 

A higher surface temperature in turn can induce an increase of the material quantity removed per laser pulse. This can make the ablation process more efficient. Nevertheless thermal damage of the material or melt and debris formation must be avoided. 

In addition, as a typical failure mechanism, fiber/matrix debonding occurs due to the shear and tension type loading. If fiber/matrix debonding has taken place, the local separation initiates additional fiber cracking, wear debris formation, and a more intensive wear process. In the steady state wear process, a so-called compacted wear debris layer (CWDL) covers the surface it is composed of pulverized wear debris and matrix material. During the wear process, this layer is continuously formed and removed by the surfaces sliding over each other. 

Transient sources of solids and gases (due to debris formation or degassing of system)... 

Chemical Wear. Chemical wear, which can be operative in both abrasive and adhesive wear types depending upon the deformational and thermal conditions, is the mechanism of wear debris formation generated as a result of some chemical reaction between the interacting materials and their environment. Such kinds of chemical reactions are also known as tribochemical reaction as they are promoted only in a tribological interaction. In the case of polymers sliding against metal surfaces, there are four important mechanisms by which a tribochemical reaction can be promoted (2). The first one is due to the interfacial heating... 

The precipitation of vaporised material on the surface of the structured glass causes the deposition of debris around the structure formed. The debris formation can be significantly reduced when the laser microstructuring is performed in a suitable environment [261]. Normally, the debris layer does not... 

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