| One of the primary goals of sustainable development of China’s national economy is to establish the sustainable development and application of mineral resources.The sustainable utilization capacity of mineral resources is related to a series of environmental,safety and resource waste issues.The limited mineral resources and the negative environmental and social impact of traditional manufacturing industry give rise to the demand of sustainable development.Traditional manufacturing methods such as masonry,casting,rolling,press compaction or rammer compaction are mainly used for layered forming in clay mineral industry.In material design,the traditional manufacturing process of material ratio based on experience can not achieve accurate demand performance balance,easy to cause wide selection area and small material area to meet the requirements.In the structural design,it is difficult to control the pore structure(porosity and pore size,etc.)by such traditional methods.The porous structure and geometric structure design of mineral composites can effectively realize the transmission and control of energy,and also has the advantage of controllable physical properties.Therefore,the optimal design of mineral materials and structures can reduce material consumption and achieve high-performance control,which is very important for sustainable manufacturing.Additive manufacturing can effectively utilize materials to form high-performance objects with complex structures.Direct ink writing technology has become one of the key technologies to improve the mineral value and broaden its application fields.Among the mineral materials,kaolinite composites are one the first mineral materials for direct ink writing technology to effectively control its pore structure and further enhance its physical and chemical properties.However,the key problem of multi-structure design for sustainable manufacturing has not been solved by the single nozzle forming of kaolinite composites,which obviously lacks the adjustability of material and pore.The research focuses on the key problems of multi-structure design and manufacturing in the sustainable application of kaolinite minerals.At present,kaolinite composites have not developed innovative products with complex microstructure and designable material properties,realizing the integrated control of physical models with multi-structure.As a doctoral research project,a new multi-structure design method based on direct ink writing process for kaolinite composites,especially the combination of multi-material and pore design is proposed,which shows excellent prospects in the field of innovative application and low-carbon design and manufacturing.There are four parts in this paper:(1)The mechanical device,control system and printing process of the platform for kaolinite-based composites were studied,and a complete mechanical control platform was built.The best gradient printing effect was obtained with the parameters of 0.5 mm layer thickness and 150 mml/s flowrate and 0.4 mm nozzle size.It was found that the forming quality has no correlation with the change of moving speed.The appropriate parameters were the distance of 2 mm between nozzle and platform and the retraction distance of 0.6 mm.The forming law affected by many factors was established,and the control method of printing parameters of kaolinite composite was formed.(2)The influence of the composition of kaolin and the ratio of wax-based additives on the mechanical properties of the soft clay was revealed.The compression coefficient was greater than 0.4 MPa,and the internal friction angle was within 1°-44°,The range of cohesive force was 3-34 k Pa,which met the requirements of typical soil with wide range of real demand.The results showed that the volume of most holes was less than9.25 mm~3,the flatness value was between 0.58 and 0.80,the distribution of hole angle has a certain symmetry,and the number of holes along the given symmetry line was similar.The bionic gradient pore structure and the bionic characteristics of micro nano pores were revealed through the formation of bionic gradient pore and double gradient change of material.(3)It was found that the addition of 15 wt.%diamond could effectively delay the curing time and improve the printing efficiency.There was a gap between the stacked layers with the layer by layer printing method,and the throat radius distribution was concentrated in the position less than 0.16 mm,of which 25μm was the peak of the maximum distribution.Secondly,the layered pores along the XYZ axis provided an effective method for transverse heat conduction.The results showed that the aggregation and growth of emissive mullite phase was due to the thermal insulation of diamond and the decrease of crystallization temperature,which significantly enhanced the mechanical properties.Diamond also has good thermal conductivity,which can avoid cracks not only in the early stage of polymer hydrothermal reaction,but also in the high temperature above 1200℃.(4)In order to verify and simulate the structure of gradient kaolin based soft soil bionic material,rhino and other three-dimensional modeling software were used to reconstruct the pore structure with the software independently developed by Simpleware,φ(Friction angle),α(Pore local angle)andΨ(Z.T)(penetration rate)was highly related to the pore structure of the printed sample,which can be accurately controlled and designed by the connectivity and shape of the pore.The structural verification and simulation of diamond reinforced kaolinite composites showed that the 3D structure with connected pores(Schwarz w 3D)could bring better balance of mechanical and thermal insulation properties,and effectively reduce the influence of internal random pores on shear stress.The applications of land on life,industry innovation and infrastructure,responsible production and consumption were expanded by combining gradient forming multi-structure bionic kaolinite soft clay and diamond reinforced kaolinite composites,which provides a new idea for exploring sustainable application of additive manufacturing mineral materials. |
