Investigation on Residual Strength and Failure Mechanism of the Ceramic/UHMWPE Armors after Ballistic Tests.

In this paper, the ballistic damage mechanism and residual bearing capacity of ceramic/backing plate armor were investigated. First, a series of lightweight armors were prepared, consisting of ceramic and ultra-high molecular weight polyethylene fiber-reinforced resin matrix composite (UHMWPE) plates, and were wrapped in a high-strength fabric. Then, the ceramic/UHMWPE armors were hit by one or two bullets, and finally subjected to compression testing. The results showed that the main failure mode of integral ceramic/UHMWPE armors was ceramic brittle fracture. Many zigzag patterns on the compression curve indicated that the specimens had undergone the stages of crack propagation, ceramic fragment reorganization, plastic deformation of UHMWPE backing plate, interlaminar tearing, and overall fracture. The failure of spliced ceramic/UHMWPE armors was mainly due to the dislocation between ceramic sheets; the smooth compression curves indicated that there was no recombination of ceramic fragments and obvious interlayer debonding during the compression. Under the maximum load, each ceramic/UHMWPE armor with ballistic damage did not suddenly break and fail. The structure and thickness of ceramic plates all had an impact on residual strength: under the same structure, the greater the thickness, the greater the residual strength, but the relationship between them was not linear; under the same thickness, the residual strength of the spliced ceramic/UHMWPE armor was higher. The residual strength was also related to the number of shots: after two bullets hit, its value was only one-third of that after one bullet hit.

Investigation on the promotional role of Ga2O3 on the CuO-ZnO/HZSM-5 catalyst for CO2 hydrogenation.

Dimethyl ether (DME) can be directly synthesized from carbon dioxide and hydrogen by mixing methanol synthesis catalysts and methanol dehydration catalysts. The activity and selectivity of the catalyst can be greatly affected by the promoter; herein, we presented a series of CuO-ZnO-Ga2O3/HZSM-5 hybrid catalysts, which were prepared by the coprecipitation method. The effect of the Ga2O3 content on the structure and performance of the Ga-promoted Cu-ZnO/HZSM-5 based catalysts was thoroughly investigated. The results showed that the addition of Ga2O3 significantly increased specific surface areas and Cu areas, decreased the size of Cu particles, maintained the proportion of Cu+/Cu0 on the surface of the catalyst, and strengthened the metal-support interaction, resulting in high catalytic performance.

Phosphorus pentoxide/metal chloride mediated efficient and facile catalytic conversion of fructose into 5-hydroxymethylfurfural.

Phosphorus pentoxide (P2O5)/metal chloride mixtures could significantly improve 5-HMF yield and selectivity for the catalytic conversion of fructose under mild conditions, whereas neither P2O5 nor tested metal chloride alone gave reasonable performances. A maximum 5-HMF yield of 75% with ∼85% selectivity could be achieved within 30 min at 80 °C.

Cleaving the ß--O--4 bonds of lignin model compounds in an acidic ionic liquid, 1-H-3-methylimidazolium chloride: an optional strategy for the degradation of lignin.

The hydrolysis of ß--O--4 bonds in two lignin model compounds was studied in an acidic ionic liquid, 1-H-3-methylimidazolium chloride. The ß--O--4 bonds of both guaiacylglycerol-ß-guaiacyl ether and veratrylglycerol-ß-guaiacyl ether underwent catalytic hydrolysis to produce guaiacol as the primary product with more than 70 % yield at 150 °C. Up to 32 wt % substrate concentration could be treated in the system without a decrease in guaiacol production. The ionic liquid could be reused without loss of activity in guaiacol production from both guaiacylglycerol-ß-guaiacyl ether and veratrylglycerol-ß-guaiacyl ether. A possible mechanism accounting for the guaiacol production is presented.