常用的硬化方法主要有以下两种：
Commonly used hardening methods are mainly of two kinds:
1、普通CO2气硬法
1. Common CO2 gas hardening method.
此法是水玻璃粘结剂领域里应用最早的一种快速成型工艺，由于设备简单，操作方便，使用灵活，成本低廉，在国内外大多数的铸钢件生产中得到了广泛的应用。
This method is the earliest rapid prototyping process in the field of sodium silicate binder. Because of its simple equipment, convenient operation, flexible use and low cost, it has been widely used in the production of most steel castings at home and abroad.
CO2气体硬化水玻璃砂的主要优点是：硬化速度快，强度高；硬化后起模，铸件精度高。
The main advantages of CO2 gas hardening sodium silicate sand are fast hardening speed, high strength, and high casting precision after hardening.
普通CO2气体硬化水玻璃砂的缺点是：型（芯）砂强度低，水玻璃加入量（质量分数）往往高达7~8%或者更多；含水量大，易吸潮；冬季硬透性差；溃散性差，旧砂再生困难，大量旧砂被废弃，造成环境的碱性污染。
The shortcomings of ordinary CO2 gas hardened sodium silicate sand are: low strength of mold (core) sand, the addition of sodium silicate (mass fraction) often as high as 7-8% or more; high moisture content, easy to absorb moisture; poor hardness and permeability in winter; poor collapsibility, difficult regeneration of used sand, a large number of used sand abandoned, resulting in alkaline pollution of the environment.
2、有机酯自硬法
2, organic ester self hardening method
此法是采用液体的有机酯代替CO2气体作水玻璃的硬化剂。
This method uses liquid organic ester instead of CO2 gas as hardener for water glass.
这种硬化工艺的优点是：型（芯）砂具有较高的强度，水玻璃加入量可降至3.5%以下；冬季硬透性好，硬化速度可依生产及环境条件通过改变粘结剂和固化剂种类而调整（5~150min）；型（芯）砂溃散性好，铸件出砂清理容易，旧砂易干法再生，回用率≥80%，减少水玻璃碱性废弃砂对生态环境的污染，节约废弃砂的运输、占地等费用，节约优质硅砂资源；型砂热塑性好，发气量低，可以克服呋喃树脂砂生产铸钢件时易出现的裂纹、气孔等缺陷；可以克服CO2水玻璃砂存在的砂型表面稳定性差、容易过吹等工艺问题，铸件质量和尺寸精度可与树脂砂相媲美；在所有自硬砂工艺中生产成本最低，劳动条件好。
The advantages of this hardening process are: the mold (core) sand has high strength, the addition of sodium silicate can be reduced to less than 3.5%; the hardening rate can be adjusted according to the production and environmental conditions by changing the types of binder and hardener (5-150 min); the mold (core) sand collapsibility is good, the casting sand is easy to clean up, old. The sand is easy to be regenerated by dry method, and the recycling rate is more than 80%. It can reduce the pollution of alkaline waste sodium silicate sand to the ecological environment, save the transportation and land occupation of the waste sand, save the high quality silica sand resources. CO2 sodium silicate sand has some technical problems, such as poor surface stability of sand mold, easy overblowing and so on. The quality and dimension precision of the castings can be comparable with resin sand.
该硬化工艺的主要缺点是：型芯砂硬化速度较慢，流动性较差。
The main drawback of the hardening process is that core sand is slow in hardening and poor in fluidity.
目前铸造生产中，有时采用复合硬化工艺，例如短时吹CO2达到起模强度后先起模，再吹热空气，或烘干，或利用有机酯自硬，或自然脱水干燥，以获得较大的终强度，提高生产效率。
At present, compound hardening technology is sometimes used in foundry production, such as blowing CO2 for a short time to reach the strength of the mold first, then blowing hot air, or drying, or using organic esters to harden themselves, or natural dehydration drying, in order to obtain greater final strength and improve production efficiency.