Anchor bolts are commonly used throughout underground mining and tunnelling operations to improve roof stability.However,premature failures of anchor bolts are significant safety risks in underground excavations aroun...Anchor bolts are commonly used throughout underground mining and tunnelling operations to improve roof stability.However,premature failures of anchor bolts are significant safety risks in underground excavations around the world due to susceptible bolt materials,a moist and corrosive environment and tensile stress.In this paper,laboratory experiments and hydrogeochemical models were combined to investigate anchor bolt corrosion and failure associated with aqueous environments in underground coal mines.Experimental data and collated mine water chemistry data were used to simulate bolt corrosion reactions with groundwater and rock materials with the PHREEQC code.A series of models quantified reactions involving iron and carbon under aerobic and anaerobic conditions in comparison with ion,pH and pE trends in experimental data.The models showed that corrosion processes are inhibited by some natural environmental factors,because dissolved oxygen would cause more iron from the bolts to oxidize into solution.These interdisciplinary insights into corrosion failure of underground anchor bolts confirm that environmental factors are important contributors to stress corrosion cracking.展开更多
The electrical properties of chemically derived graphene and graphene grown by chemical vapor deposition （CVD）, until now, have been inferior to those of mechanically exfoliated graphene. However, because graphene i...The electrical properties of chemically derived graphene and graphene grown by chemical vapor deposition （CVD）, until now, have been inferior to those of mechanically exfoliated graphene. However, because graphene is easier to produce in large quantities through CVD or growth from solid carbon sources, it has a higher potential for use in future electronics applications. Generally, modifications to the pristine lattice structure of graphene tend to adversely affect the electrical properties by shifting the doping level and changing the conductivity and the mobility. Here we show that a small degree of graphene surface functionalization, using diazonium salts with electron-withdrawing and electron-donating functional groups, is sufficient to predominantly induce p-type doping, undiminished mobility, and higher conductivity at the neutrality point. Molecules without a diazonium anchor group desorb easily and do not have a significant effect on the electronic properties of graphene devices. We further demonstrate the variability between identically fabricated pristine devices, thereby underscoring the caution needed when characterizing graphene device behaviors lest conclusions be drawn based on singular extremes.展开更多
基金Project(140100153)supported by Australian Research Council Linkage Grant。
文摘Anchor bolts are commonly used throughout underground mining and tunnelling operations to improve roof stability.However,premature failures of anchor bolts are significant safety risks in underground excavations around the world due to susceptible bolt materials,a moist and corrosive environment and tensile stress.In this paper,laboratory experiments and hydrogeochemical models were combined to investigate anchor bolt corrosion and failure associated with aqueous environments in underground coal mines.Experimental data and collated mine water chemistry data were used to simulate bolt corrosion reactions with groundwater and rock materials with the PHREEQC code.A series of models quantified reactions involving iron and carbon under aerobic and anaerobic conditions in comparison with ion,pH and pE trends in experimental data.The models showed that corrosion processes are inhibited by some natural environmental factors,because dissolved oxygen would cause more iron from the bolts to oxidize into solution.These interdisciplinary insights into corrosion failure of underground anchor bolts confirm that environmental factors are important contributors to stress corrosion cracking.
文摘The electrical properties of chemically derived graphene and graphene grown by chemical vapor deposition （CVD）, until now, have been inferior to those of mechanically exfoliated graphene. However, because graphene is easier to produce in large quantities through CVD or growth from solid carbon sources, it has a higher potential for use in future electronics applications. Generally, modifications to the pristine lattice structure of graphene tend to adversely affect the electrical properties by shifting the doping level and changing the conductivity and the mobility. Here we show that a small degree of graphene surface functionalization, using diazonium salts with electron-withdrawing and electron-donating functional groups, is sufficient to predominantly induce p-type doping, undiminished mobility, and higher conductivity at the neutrality point. Molecules without a diazonium anchor group desorb easily and do not have a significant effect on the electronic properties of graphene devices. We further demonstrate the variability between identically fabricated pristine devices, thereby underscoring the caution needed when characterizing graphene device behaviors lest conclusions be drawn based on singular extremes.
