一种铸造用复合改性水玻璃粘结剂的研究

Study on a Compound Modified Sodium Silicate Binder for Casting

以钠水玻璃作为粘结剂主体,为了进一步提高粘结剂的抗拉强度,对水玻璃进行了复合改性。首先通过对比试验确定了改性剂的种类,然后通过正交试验优化了粘结剂组分配比(质量比):钠水玻璃:氢氧化钾:氢氧化钠:H剂:三聚磷酸钠=1000:30:40:20:15。改性后粘结剂的粘度为362.5 mPa·s,密度为1.59 g/cm^(3)。在粘结剂加入量为(占砂重)4%,吹气时间为60 s的条件下,试样即时抗拉强度为0.19 MPa,24 h抗拉强度达到1.26 MPa。当吹气时间超过60 s,低于120 s,随着吹气时间的延长,试样的初始强度有所增强,24 h抗拉强度无明显下降趋势。复合改性对改善水玻璃砂抗“过吹”效果明显。该粘结剂发气量低,溃散性好,具备优良的综合工艺性能。

In this paper,a sodium silicate was used as the main part of the binder,in order to further improve the tensile strength of the binder,and the water glass was modified inorganically.The types of modifiers were first determined through comparative experiments,and the optimal ratio of modifiers was determined through orthogonal experiments.The research results showed that the optimal ratio(mass ratio)of the modified water glass was:water glass:KOH:NaOH:H agent:sodium tripolyphosphate=1000:30:40:20:15,the viscosity of 4%the modified binder was 362.5 mPa·s and the density was 1.59 g/cm^(3).When the amount of binder added(accounting for the weight of sand)was 4%,and the blowing time was 60 s,the instant tensile strength of the sample was 0.19 MPa,and the tensile strength of the sample reached 1.26 MPa for 24 h.When the blowing time was more than 60 s and less than 120 s,the initial strength of the sample increased with the extension of the blowing time,and the 24 h tensile strength had no obvious downward trend.The compound modification has an obvious effect on improving the resistance of the sodium silicate sand to“overblowing”.The binder has low gas evolution,good collapsibility,and excellent comprehensive process performance.