In this paper, the adsorption effect of CO2 at 5 different MDEA-TETA mix ratios, and the optimum ratio is MDEA: TETA=1:9. More study was done on the absorption kinetics under the optimum ratio to draw the reaction order and the average activation energy. The results are as follows: the activation order n=1.22, the reaction rate constant K'=0.28.

The superstructure phenomenon in Ti3Siy-xAlxCz interlayer solid solution ceramics was found and studied. It is showed that in the X-ray diffraction patterns of the interlayer solid solution Ti3Si0.9Al0.3C1.93 and Ti3Si0.8Al0.4C1.93 bulk samples, which were in-situ reactively synthesized by hot-pressing the elemental Ti, Si, Al and C (graphite) mixed powders, the diffraction peaks of [00L] crystal planes are very weak, there is only a small diffraction peak belonging to the [008], and the diffraction peaks belonging to [0021, [004] and [0061 crystal planes almost not exist. However, all diffraction peaks belonging to [00L] crystal planes appear in the x-ray diffraction pattern of the powders taken from the bulk samples. This superstructure phenomenon demonstrates that the Ti3Si0.9Al0.3C1.93 and Ti3Si0.8Al0.4C1.93 bulk samples indeed are random solid solution. Due to the internal stresses releasing, the powders taken from the bulk samples generated a transition from random state to order, consequently the x-ray diffraction patterns of the powders presented stronger [00L] crystal plane diffraction peaks. This superstructure phase-change may take some fundamental effects on performances of the Ti3Si0.9Al0.3C1.93 and Ti3Si0.8Al0.4C1.93 bulk materials.

High purity Ti3Si0.8Al0.4C1.95 layered solid solution ceramic has been fabricated by in-situ hot-pressing from titanium, silicon, aluminum, and graphite elemental powders. The effect of the synthesis temperature to the purity of the product, the phase composition and the microstructure of the product were analyzed, and the density, flexural strength and resistivity were also analyzed. The result indicates that the appropriate temperature for hot-pressing is about 1550 V, but higher or lower temperature will lead to the appearance of the TiC and Ti5Si3; the grains have a typical platelike shape, and layered structure could be seen clearly from the SEM micrograph; the density, flexural strength and resistivity of the Ti3Si0.8Al0.4C1.95 are all between those of pure Ti3SiC2 and Ti3AlC2.

A search for Ti3Si1.2-xAlxC2 (x=0~1.2) solid solution was undertaken using precise X-ray diffraction measurements. The samples covering the whole concentration range were studied. Except very ends of the concentration range, the samples contained two phases, identified as Ti3Si1.2-xAlxC2 solid solution and TiC respectively. Lattice parameter, a increased, c increased, c/a increased, and cell volume increased with the increasing of Al concentration.

In this study, free Ti/Si/Al/C powder mixtures with molar ratios of 3:0.8:0.4:1.8 were heated in argon with various schedules, in order to reveal the possibility for the synthesis of high Ti3Si0.8Al0.4C1.8 content powder. X-ray diffraction (XRD) was used for the evaluation of phase identities of the powder after different treatments. Scanning electron microscopy (SEM) was used to observe the morphology of the Ti3Si0.8Al0.4C1.8 solid solution. XRD results showed that predominantly single phase samples of Ti3Si0.8Al0.4C1.8 were prepared after heating at 1450 degrees C for 5 min in argon and the lattice parameters of Ti3Si0.8Al0.4C1.8 lay between those of Ti3SiC2 and Ti3AlC2. SEM observation showed that the grains of Ti3Si0.8Al0.4C1.8 solid solution exhibited a lamellar shape, which is a characteristic feature of Ti3SiC2 and Ti3AlC2. (C) 2006 Elsevier B.V. All rights reserved.

A search for Ti3Si1.2-xAlxC2 (x=0∼1.2) solid solution was undertaken using precise X-ray diffraction measurements. The samples covering the whole concentration range were studied. Except very ends of the concentration range, the samples contained two phases, identified as Ti3Si1.2-xAlxC2 solid solution and TiC respectively. Lattice parameter, a increased, c increased, c/a increased, and cell volume increased with the increasing of Al concentration.

A search for Ti3Si1.2-xAlxC2 (x=0~1.2) solid solution was undertaken using precise X-ray diffraction measurements. The samples covering the whole concentration range were studied. Except very ends of the concentration range, the samples contained two phases, identified as Ti3Si1.2-xAlxC2 solid solution and TiC respectively. Lattice parameter, a increased, c increased, c/a increased, and cell volume increased with the increasing of Al concentration.