Advanced Ceramics - Features and Applications of Silica/Zircon Ceramics for Metal Casting

Ceramic cores allow the creation of internal cavities during the investment casting process that are too complex or too small to be “shelled”. This allows turbine engine blades and vanes to be cast to size with complex cooling passages, which allow engines to operate at higher temperatures with greater efficiency. Ceramic cores are also used to create undercuts and hosels in golf clubs, pump impellers, valve bodies, and fuel system mixing components.

In addition to ceramic cores, Certech manufactures silica cores, porous ceramics and various foundry supplies such as pouring filters, cups, snouts, collars, funnels and extruded diameters. Decorative ceramics are also produced, including jewelry, picture frames and ornaments.

Manufacturing of Certech Metal Casting

Certech manufactures these products using a proprietary low-pressure injection molding process and a proprietary firing process, which have been specifically designed with high volume and short lead-time in mind. This allows Certech to generate sample volumes as quickly as five days, and routinely produce production volumes with a two-week lead-time. Another advantage of this the proprietary Certech process is that it is extremely low wear, allowing hardened steel dies to routinely produce in excess of 100,000 cores.

Application of K-278 Ceramics for Metal Casting

Small, thin cross section parts where good thermal stability is required. Used for high temperature preheat applications in equiax casting or in DS and SX applications where a silica/zircon composition is a better match to the casting process than an all silica composition.

Chemical Composition of K-278 Ceramics for Metal Casting

The chemical composition of the K-278 ceramic for metal casting is outline in the following table.

Table 1. Chemical composition of K-278 ceramic for metal casting

Name

Formula

Typical %

Silica

SiO2

74

Zircon

ZrSiO4

24

Alumina

Al2O3

1

Other

-----

<1

Trace Element Analysis of K-278 Ceramics for Metal Casting

The trace element analysis of the K-278 ceramic for metal casting is outline in the following table.

Table 2. Trace element analysis of K-278 ceramic for metal casting

Element

Symbol

Typical ppm

Iron

Fe

<900

Bismuth

Bi

<0.2

Lead

Pb

<1.0

Silver

Ag

<10.0

Antimony

Sb

<5.0

Tin

Sn

<1.0

Zinc

Zn

<50.0

Cristobalite Content Range

The cristobalite content range of the K-278 ceramic for metal casting is outline in the following table.

Table 3. Cristobalite content range of theK-278 ceramic for metal casting

Property

Typical %

After Fire

8.0

After 30 minutes @1530°C

35.0

Process Shrinkage (Mold to Fired)

The process shrinkage of the K-278 ceramic for metal casting is outline in the following table.

Table 4. Process shrinkage of the K-278 ceramic for metal casting

Property

Typical %

Length

1.35

Chord (width)

1.65

Modulus of Rupture

The modulus of rupture of the K-278 ceramic for metal casting is outline in the following table.

Table 5. The modulus of rupture of the K-278 ceramic for metal casting

Property

Typical p.s.i.

@RT

2000

@RT after 1 hour @1530ºC

521

@1150ºC (heat @300ºC/hour to 1150ºC, hold 10 minutes, break)

3468

1475ºC

3437

Thermal Expansion of K-278 Ceramics for Metal Casting

The thermal expansion of the K-278 ceramic for metal casting is outline in the following table.

Table 6. The thermal expansion of the K-278 ceramic for metal casting

Property

Typical

@1000°C (x10-6/°C)

2.50

Physical Properties of K-278 Ceramics for Metal Casting

The physical properties of the K-278 ceramic for metal casting is outline in the following table.

Table 7. The physical properties of the K-278 ceramic for metal casting is outline in the following table.

Property

Typical

Bulk Density

1.83 g/cc

Apparent Density

2.56 g/cc

Porosity

28.0%

Absorption

15.0%

Core - Metal Reaction

Compatible with most nickel based, DS and SX alloys

Leachability of K-278 Ceramics for Metal Casting

30% boiling KOH
30 grams sample
30 minutes
50% leached

Creep Test of K-278 Ceramics for Metal Casting

RT to 1475ºC @ 300ºC/hour. Hold for 1 hour. Cool @ 600ºC/hour.
Test bar dimensions: L -6", C/W -1/2", P -1/4"

Pressure (p.s.i.)

Deflection (inches)

200

0.095

150

0.540

This information has been sourced, reviewed and adapted from materials provided by Morgan Advanced Materials.

For more information on this source please visit Morgan Advanced Materials.

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