Research And Development Of Microporous Ceramic Infiltration Irrigation Pipeline Based On Slip Casting Method

Infiltration irrigation is one of the most advanced agricultural water-saving irrigation technologies in the world,with the advantages of low evaporation loss,high water utilization efficiency and significant yield and income increase,which can directly transport water to the roots of crops.At present,infiltration irrigation pipes are mainly made of plastic processing,but plastic infiltration pipes have problems such as poor water permeability uniformity and difficulty in degrading plastic to produce white pollution,which affects their large-scale promotion and application.Ceramic infiltration irrigation pipes have advantages such as environmental protection,high strength,and uniform pore distribution,but there are problems such as non-standard preparation processes and large manufacturing deviations.Therefore,this paper adopts the slip casting method to develop a kind of microporous ceramic infiltration irrigation pipe based on the microporous ceramic material.On the basis of studying the effects of deflocculants and water amount blended on slurry viscosity,the influence of raw material formula and drying process on the material properties and hydraulic performance of microporous ceramic infiltration irrigation pipe was mainly analyzed,and the appropriate raw material formula and drying process were preliminarily determined;a soil water movement model for microporous ceramic infiltration irrigation was constructed,and revealed the soil water movement characteristics under different soil textures and working parameters;on this basis,combined with the distribution characteristics of crop roots and field planting methods,technical parameters for the field application of microporous ceramic infiltration irrigation pipes suitable for different crops are preliminarily proposed.The main conclusions are as follows:(1)The appropriate deflocculant and water amount blended for slip casting slurry were determined.The effect of three types of deflocculants(sodium silicate,sodium humate,and anhydrous sodium carbonate)on the viscosity of the slurry was studied,and the results showed that the effect of sodium humate on the viscosity of the slurry is not significant,while sodium silicate and anhydrous sodium carbonate have a more significant effect.With the increase of the dosage of sodium silicate and anhydrous sodium carbonate,the viscosity of the slurry shows a trend of first decreasing and then increasing.When the dosage of sodium silicate and anhydrous sodium carbonate is 1% and 0.8%,the viscosity of the slurry reaches the minimum value,with relative viscosity values of 1.81 and 2.28.In addition,the viscosity of the slurry decreases rapidly with the increase of water amount blended.When the water amount blended exceeds 34%,the decrease in viscosity slows down.Considering the forming requirements of the green body,the appropriate deflocculant is determined to sodium silicate,with a dosage of 1%;and the appropriate amount of water blended is 34%.(2)The suitable raw material formula for preparing microporous ceramic infiltration irrigation pipe were determined.The effects of solid content and water amount blended ratio,skeleton material and pore-forming agent ratio in solid content,and skeleton material particle size on the material formula(porosity,flexural strength,and curvature)and hydraulic performance(flow rate)of microporous ceramic infiltration irrigation pipe were studied.The results show that as the solid content and water amount blended ratio increased,the porosity and flow rate of the pipe under the same working pressure increase,while the flexural strength decrease;But when the ratio exceeds 64:36,the internal binding force of the embryo is sufficient,the porosity and flow rate under the same working pressure decrease,and the flexural strength increases;and the curvature continues to decrease with the increase of the ratio.The ratio of skeleton materials and pore-forming agents significantly affects the porosity of pipe.When the ratio changes from 90:10 to 75:25,the porosity increases by 11.2%,and the curvature and flow rate under the same working pressure increase to a certain extent,but the flexural strength decreases.As the particle size of the skeleton material increases,the spacing between particles increases,resulting in an increase in the porosity and flow rate under the same working pressure,and a decrease in flexural strength and curvature.Taking into account the requirements for pipe transportation,installation and usage,a suitable raw material formula for preparing microporous ceramic infiltration irrigation pipes is preliminarily proposed: clay is selected as the skeleton material,with a particle size of 0.180-0.355 mm;slag is selected as the pore-forming agent,and the particle size is required to be less than 0.355 mm;sodium silicate is selected as the deflocculant;the mass ratio of skeleton material,pore-forming agents deflocculant,and water is 55:10:1:34.(3)The drying parameters for the preparation process of microporous ceramic infiltration pipe were clarified,and the standardized preparation method for microporous ceramic infiltration irrigation pipes based on injection molding method was proposed.A rise in drying temperature will increase pipe shrinkage and reduce the impact of free liquid on pore structure.The porosity,flexural strength,curvature and flow rate under the same working pressure will increase,but excessive temperature will reduce the yield.The appropriate drying temperature is 75 ℃.When the moisture content of the dry body exceeds 16%,there is more free liquid in the green body,which has a more significant impact on the pore structure,resulting in a decrease in the porosity,yield and flow rate under the same working pressure,an increase of flexural strength and curvature increase,and the appropriate moisture content of the dry body is 16%.Taking into account the preparation cost and properties requirements of infiltration irrigation pipe,a standardized preparation process for microporous ceramic infiltration pipes based on injection molding method is proposed:(1)raw material treatment: including impurity removal,crushing,screening,and batching;(2)mixing: first dissolve sodium silicate in water,then mix with solid phase materials and stir at low speed for 30 minutes;(3)slip casting: including 5 processes of grouting,suction,return,standing and demolding,with suction for 12 minutes and standing for 24 hours;(4)drying: use a constant temperature drying oven for drying,with a drying temperature of 75℃,a drying time of 2 hours,and a moisture content of 16% for the dried product;(5)sintering:tunnel furnace sintering is used,with a sintering temperature of 1085℃,then obtain microporous ceramic infiltration irrigation pipes.(4)The suitable application technical parameters for microporous ceramic infiltration irrigation pipelines for different crops were preliminarily determined.A mathematical model for soil moisture movement under microporous ceramic infiltration irrigation was constructed and its accuracy was verified through experiments;analyzed the effects of different soil textures and working parameters(working pressure,burial depth,permeability coefficient)on soil water movement under microporous ceramic infiltration irrigation through mathematical model.According to the type of root system,four typical crops were selected: scallions(fibrous root system),Chinese cabbage(shallow straight root system),peanuts(deep straight root system),and white radish(tuberous root system).On the basis of soil water movement patterns of microporous ceramic infiltration irrigation,combined with the distribution characteristics of crop roots and field planting methods,technical parameters such as working pressure,burial depth,permeability coefficient,and pipe spacing of micro porous ceramic infiltration irrigation pipelines were preliminarily determined.For scallions,the suitable working pressure,burial depth,and permeability coefficient of pipelines in clay loam soil are 2-3 k Pa,5-10 cm,and 0.5-1 cm/h.The pipeline layout is three rows in one pipe and the pipe distance is 45 cm.For cabbage,the suitable working pressure,burial depth,and permeability coefficient of the pipeline in loam soil are1-2 k Pa,10-15 cm,and 0.3-0.5 cm/h.The pipeline layout is two rows in one pipe and the pipe distance is 55 cm.For peanuts,the suitable working pressure,burial depth,and permeability coefficient of pipelines in sandy soil are 0.5-1 k Pa,15-20 cm,and 0.1-0.3 cm/h.The pipeline layout is one ridge with one pipe,and two rows in one pipe and the pipe distance is 30 cm;For white radish,the suitable working pressure,burial depth,and permeability coefficient of the pipeline in loam soil are 1-2 k Pa,15-20 cm,and 0.2-0.5 cm/h,respectively.The pipeline layout is one pipe with two rows and the pipe distance is 50 cm.