Composite produced from rice husk and chopped carbon fiber without using any binders

A composite was fabricated from agricultural waste and industrial waste, namely rice husk (RH) and carbon fiber (CF) ends. A mixture of powdered RH and chopped CFs was molded into a slab by means of hot pressing without the use of any binders, after which some samples were subjected to a post-heating process. The physical properties of bulk density, Shore hardness, bending strength, and compressive strength of composites produced at different heating temperatures and various CF fractions were subsequently evaluated. The coefficient of kinetic friction and specific wear rate at the surfaces of these composites in contact with a SUS304 stainless steel ball were also ascertained. Unfilled (CF-free) composites heated to 1000 °C displayed the greatest mechanical strength and optimal sliding properties, superior to the CF filled samples, resulting from the densification of the molded lignocellulosic elements in RH. However, this densification was accompanied by a large thermal shrinkage, causing a large molding error. The composite that contained 20% (by mass) CF and which was not subjected to a post-heating process turned out to be subject to only a minor molding error (∼1%), but was characterized by satisfactory mechanical and sliding properties: bulk density 1.19 g/cm3, Shore hardness 76.1 HS, bending strength 41.2 MPa, compressive strength 150.2 MPa, kinetic friction coefficient 0.19, and specific wear rate of 2.6 × 10−9 mm2/N. Filling CFs into composites that were then treated with a post-heating process at 800–1200 °C reduced their mechanical and sliding properties, which is associated with a difference in the thermo-mechanical properties between CFs and the RH matrix.

Composite fabricated from rice husk and carbon fiber ends without using any binders.Figure optionsDownload as PowerPoint slideHighlights
► A composite from rice husk (RH) and carbon fiber ends (CFs) was fabricated by means of hot pressing without binders.
► A composite which was molded from RH and was not filled with CFs exhibited superb mechanical and sliding properties.
► But, the above fabrication process involved a large molding error and required an additional post-heating process at 1000 °C.
► The introduction of CFs into RH-based composites resulted in satisfactory mechanical and sliding properties.
► This attained a small molding error, and did not require a post-heating process.