Study On The Preparation And Performance Of The Breathable Steel

In injection molding industry, the breathable steel is used to fabricate the mosaic block of injection mold, solving the air trapping in the injection process. At present,the common preparation methods of breathable steel materials mainly include:traditional powder metallurgy method, laser sintering, gel injection mold and powder injection molding etc. In this paper, gel-casting along with microwave sintering was used to prepare breathable steel materials. The preparation process route was developed. The pore microstructure, the mechanical properties, the breathing and machining performance of the breathable steel materials were investigated respectively.(1) The optimal gel-casting configuration is: the environmentally friendly water-based gel system and 316 L stainless steel powder as the raw material, 1%(relative to the metal powder mass fraction) sodium alginate as the dispersing agent,1%(relative to the metal powder mass fraction) gelatin as the binder, and the 56%solid content of the slurry, with a good rheological properties in billet casting.(2) The microwave sintering technology was introduced to sintering the stainless steel green body after gel-casting process. The pore microstructure changing with different sintering temperature and holding time was investigated at a same heating rate. The conclusion is as follow: with the increase of sintering temperature or holding time, the space between powder particles increases, but the porosity and the through pore rate decrease accordingly(3) For the control process of steel permeability pore microstructure in the gel-casting / composites prepared by microwave sintering, studied the preparation of powder properties on pore structure control process. Through the experiment along with theory analysis, the powder shape and particle size impacting on the pore morphology, porosity and pore size of porous stainless steel was investigated.(4) In this work, the breathable steel materials prepared by gel-casting /microwave sintering was used to fabricate the mold core. Through the experimentalmolding, the surface quality of the mold is good and the air trapping in plastic injection molding process is successfully solved. Different from the traditional injection mold using ventilation structure to solve the air trapping, breathable steel simplifies the mold structure and avoid the surface residual marks originated from the ventilation rod.The results of this work show that breathable steel with good mechanical,breathing, and machining performance can be prepared by optimizing the gel-casting slurry configuration and microwave sintering process parameter. This material could be used in injection mold and proposes a new way to solve the air trapping in the injection mold cavity...