Erosion-Resistant Zirconia Crucibles for Metal Processing

Table of Contents

Introduction
Key Features of Zirconia Crucibles
ISO-Zirconia Product Range
     Dypack-ZM Backing Material
     Dypack-Z Backing Material
     Crucible Backing Material

Introduction

Dyson Technical Ceramics™’ isostatically pressed zirconia crucibles provide high temperature resistance while also maintaining high erosion resistance. This makes it possible for the caster to operate for extended periods at higher temperatures, making zirconia the favored candidate as crucible material for applications such as:

  • Platinum/platinum group metals
  • Nickel based super alloys
  • Cobalt based super alloys
  • Uranium
  • Sputter material for hard disk drives

The use of high purity raw materials guarantees the good performance of the aforementioned products, as does the dedication of Dyson to quality. Product development at Dyson is proactive as well as reactive, as new technologies and materials are reviewed all the time and wherever appropriate included into the manufacturing facilities.

Material is selected by referring to a widespread application database, which, along with a close association with end users, offers materials with optimum performance with regard to operation and cost.

Dyson Technical Ceramics™ produces a wide variety of crucibles based on stabilized zirconia. Both the manufacturing method and the selection of the stabilizing media have an effect on the properties of the finished product.

Yttrium, calcium, and magnesium oxides are used as stabilizing agents and every product is characterized by differing thermal properties.

Key Features of Zirconia Crucibles

  • Resistance to high temperatures
  • Excellent erosion resistance
  • Increased productivity
  • Cleaner melts
  • Suitable for melting of platinum/PGM
  • Suitable for melting of nickel/cobalt based super alloys

The range of zirconia crucibles is shown in Figure 1. Figures 2, 3 and 4 depict illustrations of base profiles.

Range of Zirconia Crucibles.

Figure 1. Range of Zirconia Crucibles.

Round Internal Base Crucible.

Figure 2. Round Internal Base Crucible.

Flat Internal Base Crucible.

Figure 3. Flat Internal Base Crucible.

Rounded Internal Base Crucible.

Figure 4. Rounded Internal Base Crucible.

ISO-Zirconia Product Range

The ISO Zirconia product range includes the following:

  • ISO-Zirconia M – This high-fired magnesia stabilized zirconia exhibits excellent erosion resistance and good thermal shock resistance. It is primarily employed in vacuum furnaces.
  • ISO-Zirconia C – This variant is stabilized using calcia, and exhibits excellent thermal shock resistance good erosion resistance. It finds application in air and vacuum melting.
  • ISO-Zirconia C2 – This variety is stabilized using high-fired calcia, has good erosion resistance, good thermal shock resistance, and is used for air and vacuum melting.
  • ISO-Zirconia Y – This high-fired Ytrria stabilized zirconia exhibits excellent thermal shock resistance.

The properties of the Dyson ISO Zirconia material are listed in Table 1.

Table 1. Dyson ISO-Zirconia Material Properties

C C2 M Y
Apparent Porosity (%) 21.0 19.0 20.6 22.8
Bulk Density (g/ml) 4.37 4.58 4.46 4.49
Chemical Analysis (%)
SiO2 1.25 0.80 0.65 0.90
Fe2O3 0.10 0.10 0.15 0.13
Al2O3 1.90 0.80 0.85 1.03
CaO 4.05 03.60 0.15 0.42
MgO 0.15 0.26 2.80 0.16
ZrO2+HfO2 93.0 94.4 95.5 90.1
Y2O3 - - - 7.10
Composition (%)
Cubic Zirconia 65 75 25 75
Monoclinic Zirconia 35 25 75 25

Dypack-ZM Backing Material

  • It consists of more than 90% ZrO2 + HfO2
  • It is an excellent thermal insulator, resulting in cleaner melts, longer crucible life, and increased productivity for the caster
  • It is designed to prevent sintering

Dypack-Z Backing Material

  • 65% ZrO2, 34% SiO2
  • Good thermal insulator
  • Suitable for small installations

Crucible Backing Material

As zirconia is an outstanding insulator, Dyson™ recommends using Dypack-ZM™ Backing Material. Dypack-ZM™ is graded to prevent sintering at temperatures over 1650 °C. Dypack-ZM™ constitutes of more than 90% ZrO2 + HfO2.

The insulation properties of zirconia prevent rapid dissipation of heat from the crucible, leading to longer crucible life-spans and cleaner melts. On the other hand, for smaller installations, Dyson also suggests the use of its Dypack-Z™ backing material.

Dyson Technical Ceramics

This information has been sourced, reviewed and adapted from materials provided by Dyson Technical Ceramics.

For more information on this source, please visit Dyson Technical Ceramics.

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