Fused ceramic sand, also called as Ceramsite, is kind of man-made spherical shape ceramic particles featured by high refractoriness, low thermal expansion made by spraying melted from the fused bauxite. It provides a simple and efficient way in.
INTRODUCTION&SPECICATION
1.Introduction
Ceramsite, also called as NFS CERAMSITE-Nice Foundry Sand, is kind of man-made spherical shape ceramic particles featured by high refractoriness, low thermal expansion made by spraying melted from the fused bauxite. It provides a simple and efficient way in the foundry industry to improving the quality of the castings, reducing the production cost and avoiding environmental pollution so it is much better than silica sand. And it is also good substitution to Chromite sand and Zircon sand because of its lower price. At the present, Ceramsite is acknowledged in the worldwide as the newest and the best ideal sand for the foundries and has a very wide feasibility of applications for the future development.
2.Specification
1.Shape: Sphere
2.Angle Factor: ≤1.1
3.Refractoriness: ≥1790℃
4.Thermal expansion: 0.13% (10 minutes under 1000℃)
5.Main Chemical composition (typical value as following table):
| Unit | Al2O3 | SiO2 | Fe2O3 | TiO2 | CaO | MgO | K2O | Na2O |
| % | 75.36 | 17.72 | 2.16 | 3.23 | 0.43 | 0.35 | 0.33 | 0.08 |
3. General advantages CERAMSITE
1.Solid sphere: The shape of Ceramsite is spherical with smooth surface and less surface area and offering a very good flowability and filling ability. To compare with other sands else, less binder is used at the same mold strength and higher venting ability. It also offers the excellent collapsibility.
2.Lower thermal expansion rate: It makes the dimensions of castings better, less crack and defect and higher output.
3.Lower breakage rate: Ceramsite has a higher density and a very lower breakage rate at the reclaimation. It makes a better reclamations rate to reduce the waste sand and the pollution.
4.High refractoriness: The major chemistry is Al2O3 and SiO2, so mostly mullite and corundum phase in the Ceramsite which will make sure the high refractoriness and thermal stablity. And PH Value appears neutral. It is suitable for all kinds of metal and alloy castings.
4. Particle Size Distribution of Ceramsite
| Group | Products Code | 10 | 20 | 30 | 40 | 50 | 70 | 100 | 140 | 200 | 270 | Pan | AFS Range |
| Code | um | 1700 | 850 | 600 | 425 | 300 | 212 | 150 | 106 | 75 | 53 | Pan | |
| 20-40 | RM-200# | 15-40 | 30-55 | 15-35 | ≤3 | 15-25 | |||||||
| 30-50 | RM-300# | ≤10 | 25-45 | 35-55 | 5-15 | ≤5 | ≤2 | 25-29 | |||||
| 40-70 | RM-400# | ≤10 | 25-45 | 20-40 | 5-25 | ≤7 | ≤5 | 35-39 | |||||
| 40-100 | RM-500# | ≤3 | 10-25 | 25-40 | 25-45 | 10-25 | ≤10 | ≤5 | 45-55 | ||||
| 50-100 | RM-600# | ≤10 | 10-30 | 30-50 | 15-35 | ≤15 | ≤5 | ≤2 | ≤1 | 55-65 | |||
| 50-140 | RM-650# | ≤8 | 10-25 | 20-45 | 20-45 | 5-20 | ≤7 | ≤2 | ≤1 | 60-70 | |||
| 70-140 | RM-750# | ≤10 | 10-25 | 25-45 | 15-35 | ≤15 | ≤5 | ≤2 | 75-85 | ||||
| 100-200 | RM-1000# | ≤3 | 10-35 | 35-55 | 15-35 | ≤10 | ≤5 | 95-115 | |||||
| 140-270 | RM-1500# | ≤5 | 5-25 | 40-60 | 25-40 | ≤15 | 155-175 | ||||||
| 6-20 | NFS |
5.Application Area and its advantage compare to traditional casting sand
5.1 In Vacuum(V)-casting and Lost-foam casting (LFC)
Silica sand in dry condition largely apply in Vacuum(V)-casting and Lost-foam casting (LFC).
Silica sand create a lot of dust in process which is very bad for environment and for workers health.
Ceramsite has high refractoriness than silica sand and high density in the mold by what we can achieve high castings surface quality and decrease the unqualified castings rate.
Ball shape ceramsite has better flowability than silica sand, so it can fill the special area like inside angel, deep groove, horizontal holes easier than silica sand. So it will decrease the defects of the castings and decrease the labor volume.
According to our experience, the sand cost can decrease 90% compared to silica sand and also discharge if the waste material will also be decreased.
In LFC, if we use resin and ceramiste, the resin cost will also be decreased by 1/3.
Ceramsite price is higher than silica sand. But if we take the above advantage into consideration, ceramsite is also the good choice for you. As the ceramsite has lower expansion rate. When we produce, iron castings especially Spheroidal graphite iron castings, casting mould has limited expansion resists on the castings expansion because of graphitization. So the castings may has shringage, to avoid which casting head is needed.
5.2 In Investment Casting, ceramsite can substitute Zircon sand and powder
At present, More than 500,000 MT Investment casting in China each years and shell waste is more than 1,000,000MT. So the recycled of the shell material is an important issue.
Higher quality investment castings normally use Zircon sand and powder. But after use, it is very tough to separate with back refractories.
In Japan, people has successfully use Sintered Ceramic sand to substitute Zircon material sand and recycled ceramic sand obtained. Our ceramsite is made by fused method which has higher uniformity and smooth surface. So it can be used in Investment castings.
5.3 In large size steel castings, ceramite can substitute Chromite
Ceramiste has similar properties with chromite in thermal conductivity, thermal expansion and refractories only lower density compared with chromite. In the shape and particle strength, ceramsite is much better. But the price is only half of that of Chromite. So Ceramsite will be good choice for large size steel castings.
5.4 Resin Coated Castings
Some Resin coated sand makers has add part of ceramiste as the raw material to obtain higher refractoriness, low expanstion, easy to diffuse, higher strength and also to make special shape.
