Determination of Timing Parameters of Dust Clouds Explosion in Dependence on the Size of the Vessel Volume

EN 14034 standard defines the requirements for igniter, to determine the properties of dust clouds. The standard specifies the conditions for occurrence of explosions of dust clouds. According to the standard, equipment with a volume of 1m3 and 20L can be used to determine the explosion parameters of dispersed dusts. The equipment has the time parameters of dispersing and the ignition system defined in the Standard. Experimental determination of time parameters is required for a different chamber volume. The article therefore deals with the determination of parameters for dispersing system in the 291 litre chamber. Determination of igniter delay was performed on the base of setting the time relay. Activation of pressurised air flow was determined by calculation, and it was subsequently experimentally verified in laboratory conditions. A video camera recording was selected for measuring the rate of nitrocellulose ignition from the resistance wire. The result of this study is determination of the igniter timing in dependence of the explosion chamber volume. The time delay of the nitrocellulose igniter is 320 ms.

The Preparation and Tribological Properties of Multi-Layer Graphene as Paraffin Liquid Additives

Different thickness multi-layer graphene were prepared by the method of liquid ultrasonic stripping and characterized by XRD, SEM and TEM. Friction and wear properties of graphene liquid dispersing system were investigated using an Multi-functional reciprocating friction and wear tester in ambient condition. Results indicate that the graphene were in thickness of 10nm-100nm. Multi-layer graphene showed good anti-friction and anti-wear properties as paraffin liquid additives. Multi-layer graphene liquid dispersing system had the best tribological properties with 20N and 0.01wt%, and the average friction coefficient was 0.129, and the wear mass was 4.12×106μm3, reduced by 21.34% and 41.14% than paraffin liquid. The reason is that Multi-layer graphene could adsorb on the worn surface and form solid adsorption layer, which maked the friction and wear reduce.

The Application of Sodium Citrate in Co3O4 Nano-Particle Dispersing System

Based on the profound application, the Co3O4 was chosen to be research object; the optimized dispersing condition was studied and determined as: dosage of Co3O4 nano particle varied from 0.01 to 0.02mg/ml, sodium citrate was determined to be dispersing adjuvant with a dosage of 0.0005g/ml, ultrasonic time: 10min, and pH value was 7 to 8 when the Zeta potential was –57.1mv. After a detailed discussion of size distribution and dispersing condition, the size distribution of Co3O4 nano particle was measured with Malvern Nano Zetasizer to be 217nm.