Effect of hot-pressing process on mechanical properties and color changes of poplar powder compacts

Abstract

Binderless poplar powder compacts were prepared using the hot-pressing technology. The effect of the forming process on the mechanical properties and surface color of the poplar powder compacts was studied. The effect of forming temperature on mechanical properties and surface color was more noticeable than the forming pressure and the holding time. With the change of the forming process parameters, the static bending strength of the compacts increased first and then decreased. The overall change trend of the surface hardness increased continuously. The overall color difference (ΔE*) of the compacts increased with the change of forming process parameters and the surface color deepened gradually. The results of Fourier transform infrared (FTIR) spectroscopy showed that hemicellulose, cellulose, and lignin in the compacts were greatly affected by the forming process parameters. The degradation of hemicellulose and cellulose produced many colored substances, and the content of lignin increased. These made the surface color of compacts deepen.

Mechanical properties and forming conditions optimization of SiC ceramics using Camellia oleifera shell as carbon source

“…Warm-press forming is a technique to obtain cylindrical samples with uniform internal density and reasonable pore structure, then producing high-density and performance ceramics through sintering. 31 The warm-press forming process of ceramic blank generally refers to forming temperature, forming pressure, and holding pressure time, which are the main factors affecting the mechanical properties and microstructure of SiC ceramics. 32 This is because the ceramic blank will produce a series of complex chemical and physical changes in the forming process, such as lignin water absorption, softening point reduction, molecular chain movement freezing, lignin softening, selfadhesive, and so on.…”

“…Hence, the raw material could be warm‐press formed before reaction sintering. Warm‐press forming is a technique to obtain cylindrical samples with uniform internal density and reasonable pore structure, then producing high‐density and performance ceramics through sintering 31 . The warm‐press forming process of ceramic blank generally refers to forming temperature, forming pressure, and holding pressure time, which are the main factors affecting the mechanical properties and microstructure of SiC ceramics 32 .…”