机械外文翻译---利用超音速射流分散纳米粒子的新型湿式粉碎机

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1、外文原文：http:/  中文 3096 字  英文原文   Dispersion of nanoparticles by novel wet-type pulverizer utilized supersonic jet flow Abstract.We have examined the dispersion of barium titanate nanoparticles (BT-NPs) and have discussed the effect of air pressure supplied to the nozzle on the dispersio

2、n by using novel wet-type pulverizer utilized supersonic jet flow (SSJM). The aggregated particle size was decreased with increasing the air pressure and the collision times. In the optimized condition, almost the BT-NPs were dispersed with the primary particles, however, further excessive collision

3、 had caused reaggregations. The degree of dispersion has been affected by the air pressure. The injected droplets had formed almost the same diameter regardless of air pressure and the velocity was increased with increasing of the air pressure and reached 300 m/s. We have speculated that the shockwa

4、ve dominates the dispersion of BT-NPs. 1. Introduction Nanoparticles are required highly in many applications such as dielectric materials for electronic devices, electrode materials for secondary batteries, etc. The nanoparticles have been frequently produced by the so-called build up processes suc

5、h as hydrothermal process, coprecipitation process,and sol-gel method. For exploiting size effect of nanoparticles, it is crucial to control the dispersion and aggregation of the nanoparticles in suspension. However, nanoparticles aggregate more easily and strongly than submicron sized particles, an

6、d aggregated nanoparticles do not fragment easily.Therefore, it is quite difficult to disperse nanoparticles perfectly, and the dispersion of nanoparticles has become a fundamental technique for handling nanoparticles in industries. It has been reported that he nanoparticles were well-dispersed by u

7、sing beads mill 1. Bead milling with balls several tens of micrometers in diameter has recently been developed as a new method to disperse nanoparticles to almost primary particle size 1. However, the contamination caused by the grinded ball in bead milling was ten times higher than that caused by d

8、ry grinding 2.For providing nanoparticles dispersing method that can solve the above problem, we have developed novel wet-type pulverizer utilized supersonic jet flow (hereafter referred to as supersonic wet jet mill；SSJM). In this study, we have reported the dispersing result of barium titanate nan

9、oparticles (BT-NPs) and have discussed the effect of air pressure on the dispersion by using the SSJM. 2. Experimental apparatus and procedure 2.1. Experimental apparatus Figure1 shows schematic diagram of the SSJM (left). The right part of describes shows the internal configuration of the nozzle pa

10、rt. The compressed air (maximum air pressure was 0.6 MPa) was supplied at the top part of the nozzle. The Laval nozzle, which was used for the SSJM as 机械专业中英文文献翻译  shown in Figure1, is used to accelerate a compressed air passing through it to a supersonic speed, and upon expansion, to form the

11、exhaust flow so that the heat energy propelling the flow is maximally converted into kinetic energy. As a result, the injected droplets passing through the nozzle were accelerated to supersonic and were naturally cooled. The suspension in the feed tank was supplied to the throat of the nozzle, while

12、 controlling the volume flow through the pump tubing. The supplied suspension had been formed droplets by jet flow and had been accelerated inside the nozzle. The accelerated droplets had collided with the SiC plate. Most of the processed suspension was collected at the bottom tank, and some of the

13、processed suspension was evacuated along with the jet flow, therefore, the solvent recovery tank unit attached to the exhaust line.                 Figure 1. Schematic diagrams of supersonic wet jet                 mill

14、(left) and the nozzle part (right), showing                 approximate flow velocity (V), together with the                  effect on temperature (T) and pressure (P).  2.2. Experimental procedure Two kinds o

15、f BT-NP were used in this work. BT-NPs with the average particle size of 30 nm were synthesized by the sol-gel method 3 (referred to as sol-gel BT). Commercially available BT-NPs (BT-01, Sakai Chemical Industry, Japan) with the average particle size of 100 nm were manufactured by hydrothermal method

16、 (referred to as hydrothermal BT). A dispersant used in this study was an ammonium salt of poly (acrylic acid) (PAA-NH4+ , Mw 8000, Touagousei, Japan). The sol-gel BT was added to ethylene glycol monomethyl ether in 2 volume % (referred to as sol-gel BT suspension). PAA-NH4+ was added to distilled w

17、ater in 5 wt% against powder weight and then the hydrothermal BT was added in 20 volume percents against distilled water (referred to as hydrothermal BT suspension). Each suspension was injected under various air pressures from 0.3 to 0.6 MPa. An aggregated particle size was evaluated by dynamic lig

18、ht scattering method (DLS, Nano-ZS, Malvern,UK). A shape and microstructure of the BT-NPs were examined with a transmission electron microscope (TEM, JEM-3200EX, JEOL, Japan) and a field emission scanning electron microscope (FESEM, S-4800, Hitachi, Japan). 机械专业中英文文献翻译  For discussing the effec

19、t of air pressure on the dispersion by use of the SSJM, size and velocity distributions of droplets were measured as follows. Distilled water was injected under various air pressures from 0.3 to 0.6 MPa. The size and velocity distribution of droplets at a distance of 100 mm away from the nozzle exit

20、 were measured simultaneously by Phase Doppler Anemometry (Dantec Dynamics, Denmark) 3. Result and discussion                  Figure 2. Effect of collision number on cumulative  mean diameter of sol-gel BT suspensions under various air pressures. &n

21、bsp;  Figure 4. FESEM images of hydrothermal BT- NPs: (A) and (B) were before collision process, and (C) and (D) were after collision process for 3 times at 0.6 MPa 3.1. Dispersion of BT-NPs                          Figure2 shows

22、change of cumulative mean diameter DA, of which the value represents the average aggregated size, with collision number under various air pressures for sol-gel BT.TEM images of BT-NPs collided under various conditions were shown in Figure3. DA of the BT-NPs collided at 0.3 MPa was decreased with inc

23、reasing collision number. The BT-NPs collided for 3 times at 0.3 MPa were dispersed with almost the primary particles (as shown in Figure3(B), however, further excessive collision had caused reaggregations. Although DA collided at 0.4 and 0.6 MPa were also decreased by the collision at once or twice, DA was increased immediately. As