Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an exter...Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an external driving force for the vertical growth of SiC whiskers,facilitating the formation of a porous nanostructure that resembles coral models found in the macroscopic biological world.The porous nanostructures are beneficial for reducing thermal expansion mismatch and relieving residual stress.It is capable of eliminating the cracks on the surface of SiC coatings as well as enhancing the bonding of SiC coatings with quartz substrates to avoid coating detachment.展开更多
The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the elec...The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the electrical properties,anisotropic preferred etching by means of optical microscopy,Fourier transform infrared spectroscopy and transmission electron microscopy.It is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen concentration.Furtherly,we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diode.It is shown that the oxygen precipitations present in an "S" curve with increasing initial oxygen concentration after high temperature diffusion.The main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF),which are mainly dislocations,and a small amount of rod stacking faults.The density of B-OSF increases with the increasing initial oxygen concentration.The existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.展开更多
In order to develop high-performance diamond wheels,the vitrified bond with different contents of Li2O addition and corresponding diamond composites were prepared.The experimental results show that the addition of a s...In order to develop high-performance diamond wheels,the vitrified bond with different contents of Li2O addition and corresponding diamond composites were prepared.The experimental results show that the addition of a small content of Li2O leads the formation of the mullite phase in vitrified bond.When the Li2O content is 3wt%,the mullite content in the vitrified bond reaches the maximum.Whereas,the vitrified bond turns into a pure glass phase when the Li2O content further increases to 5wt%.The softening temperature of vitrified bond,wetting angle between the vitrified bond and the diamond film decrease with the increasing of the Li2O content.The softening point of the vitrified bond with 5wt% Li2O is 537 ℃ and the contact angle is 32°,which are 44 ℃ and 44° lower than those of the sample without Li2O.The CTE (coefficient of thermal expansion),the flexural strength and hardness of the diamond composite sample first increase and then decrease with the increasing of the Li2O content.When the Li2O addition is 3wt%,the flexural strength and hardness of the composites reaches the maximum values of 93 MPa and 98 HRB,respectively,which are 43.1% and 12.6% higher than those of the sample without Li2O.展开更多
基金Funded by the International Science&Technology Cooperation Program of Hubei Province of China(No.2022EHB024)the National Key Research and Development Plan(Nos.2018YFE0103600 and 2021YFB3703100)+1 种基金the National Natural Science Foundation of China(Nos.51872212,51972244,52002075,and 52102066)the 111 Project(No.B13035)。
文摘Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an external driving force for the vertical growth of SiC whiskers,facilitating the formation of a porous nanostructure that resembles coral models found in the macroscopic biological world.The porous nanostructures are beneficial for reducing thermal expansion mismatch and relieving residual stress.It is capable of eliminating the cracks on the surface of SiC coatings as well as enhancing the bonding of SiC coatings with quartz substrates to avoid coating detachment.
基金Funded by the National Natural Science Foundation of China (No. 62004154)。
文摘The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the electrical properties,anisotropic preferred etching by means of optical microscopy,Fourier transform infrared spectroscopy and transmission electron microscopy.It is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen concentration.Furtherly,we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diode.It is shown that the oxygen precipitations present in an "S" curve with increasing initial oxygen concentration after high temperature diffusion.The main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF),which are mainly dislocations,and a small amount of rod stacking faults.The density of B-OSF increases with the increasing initial oxygen concentration.The existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.
基金Funded by the Zhejiang Provincial Key Research and Development Project(No.2018C01076)。
文摘In order to develop high-performance diamond wheels,the vitrified bond with different contents of Li2O addition and corresponding diamond composites were prepared.The experimental results show that the addition of a small content of Li2O leads the formation of the mullite phase in vitrified bond.When the Li2O content is 3wt%,the mullite content in the vitrified bond reaches the maximum.Whereas,the vitrified bond turns into a pure glass phase when the Li2O content further increases to 5wt%.The softening temperature of vitrified bond,wetting angle between the vitrified bond and the diamond film decrease with the increasing of the Li2O content.The softening point of the vitrified bond with 5wt% Li2O is 537 ℃ and the contact angle is 32°,which are 44 ℃ and 44° lower than those of the sample without Li2O.The CTE (coefficient of thermal expansion),the flexural strength and hardness of the diamond composite sample first increase and then decrease with the increasing of the Li2O content.When the Li2O addition is 3wt%,the flexural strength and hardness of the composites reaches the maximum values of 93 MPa and 98 HRB,respectively,which are 43.1% and 12.6% higher than those of the sample without Li2O.
