P. Sampathkumaran

SEM observations of the effects of velocity and load on the sliding wear characteristics of glass fabric–epoxy composites with different fillers

The slide wear characteristics of a glass-epoxy (G-E) composite, filled with either rubber or oxide particles, were studied using a block-on-roller test configuration. Mass loss was determined as a function of sliding distance for sliding velocity between 0.5 and 1.5 m/s at three different loads of 42, 140 and 190 N. The worn surfaces were also examined by scanning electron microscopy (SEM). The study showed differing trends with load for the two types of fillers. At low loads, the oxide-filled had lower wear, while at high loads the rubber-filled composite had lower wear. The work also showed that higher loads and sliding velocities bring about changes in worn surface features such as interface separation, inclined fracture of fibres, loss of matrix as well as the appearance of debris with the two different fillers.

On the SEM features of glass–epoxy composite system subjected to dry sliding wear

The scanning electron microscope (SEM) features of glass fiber–epoxy composites subjected to sliding wear for distances ranging from 500 m to 6 km are recorded in this work. The results have shown that there is an existence of noticeable features on the worn surfaces. Thus for the longer run case interface separation is noticed, while for shorter runs matrix debris formation and occasional glass fiber fragmentation are seen. The work also highlights the effect of load and sliding velocity on the wear loss pattern.

Sliding wear studies in glass-epoxy system through scanning microscopic observations

The work reports the wear occurring in a glass-epoxy composite system as a function of sliding distance for a constant sliding velocity and applied load. It is seen that the weight loss increases with increasing distance, but the gradient maintained all through is not the same. An attempt has therefore been made to correlate the weight loss with the scanning microscopic observations on the worn surfaces. It is found that in the early part, the wear of the resin/mat layer contributes to the phenomenon. The process of breakage of fibre into fragments and the resin debris formation accounts for the wear at a much later stage. The phenomenon occurring in between these two stages, is attributed to some of the broken fibres getting lodged in the matrix and agglomeration of the debris formed from the matrix material. Other features of interest are highlighted and discussed in this report.

Processes-Induced Structural Transformations and the Impact Properties of Cr–Mn Iron Systems

High chromium irons are well known for their good wear resistance. Since they are brittle, they tend to fracture under impact. Hence, there is a need to improve the impact property with minimal reduction in wear characteristics. Towards this end, manganese, known for its tendency to retain austenite and containing 5 and 10% in chromium (∼16–19%) irons has been tried. Since the mechanical properties are microstructure sensitive, the castings are made in both metal and sand moulds followed by thermal treatment. The as-cast and heat-treated samples are examined microstructurally and then evaluated for hardness, and impact properties. While the hardness decreases with increase in manganese content from 5 to 10% irrespective of the sample condition (i.e., mould type/heat treatment adopted), the impact property shows two different trends. The 10% metal cooled manganese bearing sample exhibits higher values compared to the 5% ones. On the other hand, for the sand case, 5% manganese shows higher impact energy compared to the 10% ones. Thus, there is a reversal in the impact behavior for the same level of increase in manganese content for these two cases. These findings are correlated with the structural features noticed through microscopy.

Development of HDPE/silicon nitride nanocomposites using HDPE-g-dibutyl maleate as compatibilizer

HDPE has been known for its dielectric properties. Thus in this study, attempt has been made to improve the overall performance of HDPE composites by blending silane treated silicon nitride (SN) with HDPE using HDPE-g-dibutyl maleate (HDPE-g-DBM) as compatibilizer. A small quantity of surface modified nanoclay has also been added in order to improve the mechanical properties. The flexural, wear and thermal properties of the composites were measured according to ASTM standards. The results reveal that, both silane modification of SN accompanied by nanoclay addition has led to the substantial enhancement in flexural strength and flexural modulus. In addition, compatibilization has further improved the mechanical properties showing 10% (w/w of SN) as optimal compatibilizer content. The wear results showed that, as SN content increased, the slide wear loss decreased. TGA analysis showed that, the addition of SN along with compatibilizer improved the thermal stability of the nanocomposites.

Preparation of bio-nanocomposites of chitosan/thermoplastic starch reinforced with multiwalled carbon nanotubes

High performance bio-nanocomposites have been developed using crosslinked chitosan and thermoplastic starch along with acid functionalized multiwalled carbon nanotubes (f-MWCNT). The f-MWCNT loading was varied from 0 to 10%. A small amount of Dibutyl maleate has been added as a coupling agent, in order to improve adhesion between the biomaterials. The nanocomposites developed were characterized for flexural, wear, electrical and thermal properties as per ASTM standards. The composites containing f-MWCNTs exhibited enhanced flexural properties when compared with composites without f-MWCNTs. The wear results showed that, with the addition of f-MWCNTs the slide wear loss reduced slightly. The results revealed that, the resistivity of the nanocomposites decreased indicating the increase in conductivity of the nanocomposites.