The effect of sintering and cooling process on geometry distortion and mechanical properties transition of PTFE/Al reactive materials

In this research,the effect of the sintering and cooling process on geometry distortion and mechanical properties of PTFE/Al reactive material is investigated.Six particularly selected sintering temperatures,three different cooling modes(annealing cooling,normalizing cooling and rapid cooling),three different initial cooling temperature s,as well as six different final cooling temperatures were designed to compare the effects of sintering temperature,cooling rate,initial cooling temperature and final cooling temperature on the properties of reactive materials.Geometry distortion was quantitatively analyzed by a statistic on the dimensional changes of the specimens and microscopic morphology.A mechanical response properties transition from brittle to ductile was found and analyzed.By combining the thermodynamic properties of PTFE and unsteady heat conduction theory,mechanisms of cooling induced morphology change,temperature induced distortion and strength decrease were obtained.The results showed that the cooling rate has the most significant effect on the morphology transformation,while initial cooling temperature has more significant effect on the dimensional distortion than final cooling temperature.As to the mechanical properties transition from brittle to plastic,a more prominent effect of initial cooling temperature than cooling rate and final temperature was revealed.

Electron Momentum Distributions for 4a1 Orbitals of CFxCl4-x in Low Momentum Region： a Possible Evidence of Molecular Geometry Distortion

Electron momentum distributions for 4a1 orbitals of serial freon molecules CFaC1, CF2Cl2, and CFCl3 （CFxC14-x, x=1-3） have been reanalyzed due to the severe discrepancies between theory and experiment in low momentum region. The tentative calculations using equilibrium geometries of molecular ions have exhibited a great improvement in agreement with the experimental data, which suggests that the molecular geometry distortion may be responsible for the observed high intensities at p〈0.5 a.u.. Further analyses show that the severe discrepancies at low momentum region mainly arise from the influence of molecular geometry distortion on C-Cl bonding electron density distributions.

Synthesis and crystal structure of a Ni(II) complex with 1,7-diaminoethyl-4,10-dimethyl-1,4,7,10-tetraazacyclododecane

The crystal structure of a Ni(II) complex with 1,7-diaminoethyl-4,10-dimethyl,4,7,10-tetraazacyclododecane has been determined by X-ray diffraction method. Crystal data for NiC14H36Br2N6O: monoclinic, space group P21/n, a=0.8848(3), b=1.4656(3), c=1.5828(3) nm, β=90.47(3)°, V=2.0525 nm3, Z=4. The two pendant primary amino groups are located in cis positions in the complex, their nitrogen atoms and the four nitrogen donors of the fold tetraaza-macrocycle coordinate Ni(II) ion, forming a distorted octahedral geometry.