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The flexible X-ray protective materials are commonly made of lead rubber. They have heavy weight, high biological toxicity, poor flexibility and aging resistance. The "weak absorption zone" in the energy range of 40–88 keV threaten environmental safety and human health. Bi 2 O 3 -rubber based flexible X-ray protective materials were prepared by rubber production process. The micromorphology, shore hardness, specific gravity, mechanical properties and radiation protective properties were characterized and analyzed. The results showed that Bi 2 O 3 particles dispersed in natural rubber (R) matrix uniformly. The shore hardness of samples fluctuated between 41° and 46° with the increasing Bi 2 O 3 content, lower than the Level 1 index requirement of the hardness (≤80°) of lead-free composite protective materials. The specific gravity increased from 1.35 g/cm3 to 2.38 g/cm3, which reduced approximately 34% comparing with the commercial protective materials containing Pb. The breaking strength and breaking elongation meet the index requirements in National standard GB 16757-2016. When Bi 2 O 3 content reached 300 parts, the highest lead equivalent and maximum shielding ratio were 0.3012 mmPb and 52.95% respectively. It meets the index requirement of lead equivalent of 0.25 mmPb≤Pb≤0.35 mmPb for the front sheet of protective clothing. The effective shielding range of the protective material R/Bi 2 O 3 (100/300) was mainly in the range of incident energy of 65∼100 keV and 164–250 keV, which covered the "weak absorption zone" of lead. • Flexible lightweight Bi 2 O 3 -rubber based X-ray protective materials were prepared. • The hardness of Bi 2 O 3 -rubber based materials fluctuated between 41° and 46°. • The specific gravity of Bi 2 O 3 -rubber based materials ranged from 1.35 to 2.38 g/cm3. • The efficient shielding range of samples was 65∼100 keV and 164–250 keV. [ABSTRACT FROM AUTHOR]

Carbon fabric reinforced phenolic (CFRP) composites filled with nano-Al2O3were prepared by a dip-coating and heat molding process and the tribological properties of the resulting composites under different sliding conditions were investigated systematically on a block-on-ring test rig. The worn surfaces were observed in a scanning electron microscope (SEM) to understand the mechanism. Nano-Al2O3particles, as the filler, were effective in reducing the friction coefficient and wear rate of the CFRP composites. The steady state friction coefficient of the CFRP composites filled with 4 wt.% nano-Al2O3particles was about 65.5% of that of unfilled CFRP composites, and the wear rate, in this case, was about 74.7% of that of unfilled CFRP composites. Tribological tests under different sliding conditions revealed that the filled CFRP composites seemed to be more suitable than unfilled CFRP composites for tribological applications under higher sliding speed and load. Moreover, the wear resistances of the unfilled and filled CFRP composites were found to be related to the stability of the transfer film on the counterface. [ABSTRACT FROM PUBLISHER]

Abstract: Carbon fibers (CFs) were treated by HNO3 plus diamine modification and incorporated into polyimide (PI) matrix to prepare polymer composites. The friction and wear properties of the PI composites reinforced by untreated and treated carbon fibers (15wt.%), sliding against GCr15 steel, were studied on an M-2000 model ring-on-block test rig under dry sliding. Experimental results showed that the surface treatment largely reduced the friction and wear of CFs reinforced PI (CFs/PI) composites. The worn surface of CFs/PI composites and the transfer films formed on the surface of the counterpart ring sliding against CFs/PI composites were investigated by SEM. Compared with the untreated ones, the surface modified CFs can enhance the tribological properties of CFs/PI composite efficiently due to the improved adhesion between CFs and PI matrix. The differences in the friction and wear properties of CFs/PI composites are closely related with the sliding condition such as sliding rate and the applied load. Research results show that CFs/PI composites exhibited better tribological properties under higher load and sliding speed. [Copyright &y& Elsevier]

The article focuses on the friction and wear properties of short basalt fiber (BF) reinforced polyimide (PI) matrix composites. Short-fiber-reinforced polymers pose various engineering applications and serve as an important class of tribological (tribo)- materials. An M-2000 model ring-on-block test rig has been used to observe friction and wear behavior as PI composites slide against stainless steel rings. It concludes that PI tribological properties are enhanced by appropriate BF amounts.

Abstract: Carbon fabric (CF) was surface treated with silane-coupling agent modification, HNO3 oxidation, combined surface treatment, respectively. The friction and wear properties of the carbon fabric reinforced phenolic composites (CFP), sliding against GCr15 steel rings, were investigated on an M-2000 model ring-on-block test rig. Experimental results revealed that combined surface treatment largely reduced the friction and wear of the CFP composites. Scanning electron microscope (SEM) investigation of the worn surfaces of the CFP composites showed that combined surface modified CFP composite had the strongest interfacial adhesion and the smoothest worn surface under given load and sliding rate. SEM and X-ray photoelectron spectroscopy (XPS) study of carbon fiber surface showed that the fiber surface became rougher and the oxygen concentration increased greatly after combined surface treatment, which improved the adhesion between the fiber and the phenolic resin matrix and hence to improve the friction–reduction and anti-wear properties of the CFP composite. [Copyright &y& Elsevier]