The Uniqueness of Our Main Coating Ingredients

1. What Makes Yttrium Oxide (Yttria) Unique?

Use-Temperatures

ZYP Yttrium Oxide products have the highest thermodynamic stability since they are designed to contain the highest percentage of yttrium oxide (ΔHo298 – 455.5 kcal/ mole). With a melting temperature of 2400 C, use-temperatures to nearly 2000 C are typical for the products in most atmospheres (see individual product data for specifics). Reducing conditions with graphite lower the use-temperatures to around 1500 C.

Thermal Properties

ZYP Yttrium Oxide products have low thermal conductivity. Yttrium oxide has one of the lowest thermal conductivities of refractory oxides at high temperatures (0.007 cal/cm-sec-K at 1400 C). This property allows yttrium oxide to be used to reduce the heat flow on many substrates. Thermal expansion of yttrium oxide is moderate, like aluminum oxide.

Dielectric Properties

ZYP Yttrium Oxide products have an electrical resistivity of over 108 ohm-cm at room temperature and reportedly remain more electrically insulating at 2000 C than other refractory materials. The dielectric constant is about 12 at 102 to 106 Hz. Yttrium oxide is also transparent to microwave energy.

Chemical Resistance

ZYP Yttrium Oxide products contain minimal if any additives (see specific product data) in order to preserve the ultimate high-temperature stability of yttrium oxide. Therefore, ZYP Yttrium Oxide products have superior resistance to aggressive chemical attack at high temperatures and have superior thermal stability. This superior resistance to molten metals, glasses, slags, and salts leads to the products being used for coating crucibles and molds that handle the most highly-reactive molten materials, such as uranium, titanium, chromium, beryllium, and their alloys. Coatings of yttrium oxide are often used as barrier coatings to stop or prevent reactions, such as for diffusion bonding of reactive metals or for braze stop-off coatings.

Link to the PDF Guide:  Use Areas and Compatibility Guide

Lubricating Qualities

ZYP Yttrium Oxide products contain the highest-purity yttrium oxide which has the body-centered-cubic crystal structure and is quite soft (700 kg/mm2microhardness) at room temperature, with hardness dropping to 200 kg/mm2as the temperature increases to 1000 C. Thus, yttrium oxide becomes a very soft, formable, lubricating oxide at high-temperatures — leading to its uses for superplastic forming lubrication with titanium and specialty steels, as well as back-extrusion operations with uranium, and other forming operations.

2. What Makes Zirconium Oxide (Zirconia) Unique?

Use-Temperatures

ZYP Zirconium Oxide products have the highest use-temperatures of our paintable refractory/ceramic coatings, allowing utility of >2000 C[3632 F].   The Zirconium Oxide coatings can be used in most atmospheres (see individual product datasheets for specifics), but vacuum/reducing in contact with carbon/graphite can limit use or possibly cause reaction/carbon-contamination around 1350-1500 C.

Thermal Properties

ZYP Zirconium Oxide paints have the lowest thermal conductivity of any refractory/ceramic … resulting from zirconium oxide being the lowest thermal-conductivity oxide – 0.005-0.006 cal/cm-sec-K (2.09-2.51 Watts/m-K) for ‘dense’ zirconia from room temperature to 1400 C.  Thermal expansion is moderately-high … typically 8 to 10.5 x 10-6/C (25-1000 C) depending on ‘stabilization’ (described at Chemical Resistance).

Electrical Properties
Zirconium Oxide has electrical resistivity of 107 to 108 ohm-cm at room temperature, dropping to around 102-103 ohm-cm at 1000 C – thus has moderate high-temperature electrical conductivity.  Zirconium Oxide absorbs microwaves and readily heats when exposed to microwave energy.

Chemical Resistance

ZYP Zirconium Oxide paints are very chemically resistant — offered as:

• Partially-Stabilized – which has 4 wt.% Calcium Oxide (Calcia) incorporated into the crystal structure to move it mostly towards the “cubic” phase in preference to the “monoclinic” phase.  This Calcia also helps out the thermodynamic stability of the oxide somewhat, making the Partially-Stabilized Zirconia better for some situations … melting steel, precious metals, etc.  The Partially-Stabilized Zirconia is utilized in coatings with the designation “ZO” as well as the Z-Aerosol.
• Unstabilized – which is “natural” zirconium oxide that does not contain any added ‘stabilizer’ for making the crystal-structure ‘cubic’, which gives more-linear thermal expansion.  It is the “monoclinic” phase.  For most industrial applications, the Unstabilized version is fine.  The thermal expansion and variations of the expansion of the oxide in a PAINT does not lead to spallation/flaking etc.  Zircwash is a typical paint that uses “Unstabilized” zirconia.

NOTE:  All ZYP ZIRCONIUM OXIDE (ZIRCONIA) products are NOT ZIRCON (which is Zirconium Silicate).  This confuses some people, since the names are so similar.   The ZIRCON/Zirconium-Silicate compound is not as chemically stable as ZIRCONIUM OXIDE/Zirconia: the ZIRCON can lead to significant silicon contamination in melting operations.  ZIRCONIUM OXIDE has high stability with molten metals, only being surpassed by YTTRIUM OXIDE due to its thermodynamic stability.

Link to the PDF Guide:  Use Areas and Compatibility Guide

Other Properties of Interest

ZYP Zirconium Oxide paints are often used when melting alloys that have reactive-metal constituents such as titanium, hafnium, etc.  Also, the stabilized zirconia paints are excellent for melting platinum and its alloys. Additionally, they are all right to use with copper alloys [although not non-wetting].

3. What Makes Aluminum Oxide (Alumina) Unique?

Use-Temperatures

ZYP Aluminum Oxide coatings have high use-temperature, with usefulness to 1550-1800 C [2825-3275 F].   The Aluminum Oxide coatings can be used in most atmospheres (see individual product datasheets for specifics), but vacuum/reducing in contact with carbon/graphite can limit use or possibly cause reaction/carbon-contamination around 1500 C.

Thermal Properties

Aluminum Oxide has modestly-high thermal conductivity, similar to stainless-steel: 0.072 to 0.013 cal/cm-sec-K (30.1 to 5.4 Watts/m-K) for ‘dense’ alumina from 100 C to 1400 C.  Thermal expansion is moderate, typically 8.5 x 10-6/C (25-1000 C).

Dielectric Properties

Aluminum Oxide has electrical resistivity of 1016 ohm-cm at room temperature and thus is an excellent choice for a non-conductor.  The Dielectric Constant is about 9 (at 1 MHz), and its Dielectric Strength reportedly is 400 volts/mil.  Aluminum Oxide is transparent to microwaves.

Chemical Resistance

ZYP Aluminum Oxide paints are chemically resistant and high-purity.  In fact, our Type-A1 is 100% alumina after heating to 600 C (1112 F). Alumina paints are excellent for melting many metals.

Link to the PDF Guide:  Use Areas and Compatibility Guide

Other Properties of Interest

ZYP Aluminum Oxide “Traycoat” paints are useful for coating graphite trays used for sintering “Hard Metals” which have high cobalt-level (up to 25-27% Co).

4. What Makes Boron Nitride (BN) Unique?

Use-Temperatures

ZYP Boron Nitride is a very high temperature material. Use temperatures to 1800 C (3300 F) are possible in inert and reducing atmospheres. In vacuum atmospheres, boron nitride can be used to nearly 1400 C (2550 F) before sublimation, and in oxidizing atmospheres, use temperature is approximately 1000 C (1832 F).

Thermal Properties

ZYP Boron Nitride has very high thermal conductivity, higher than most other ceramic materials. Thermal conductivity at room temperature is about 0.08 cal/(cm-sec-K), compared with zirconium oxide of only 0.0046 cal/(cm-sec-K). This property makes ZYP Boron Nitride ideal for use as heat sinks and additives to increase the thermal conductivity of oils, coolants, potting compounds, friction plates and release agents.

Dielectric Properties

ZYP Boron Nitride possesses dielectric properties that are superior to those of dense alumina ceramics, and is an excellent low-loss insulator material. It has a dielectric constant of about 4 (half that of Al203) and a dielectric strength of nearly 1000 volts per mil, more than two times that of alumina. ZYP Boron Nitride is also transparent to microwave energy.

Chemical Resistance

ZYP Boron Nitride is completely inorganic and inert, is totally non-wetted by molten aluminum, magnesium, and their drosses, and offers exceptional non-reaction by most molten metals and slags. ZYP Boron Nitride is commonly used as a release agent and as a container material for molten salts, cryolite, aluminum, magnesium, silicon, iron, steels, copper, non-lead glasses, germanium, indium, antimony, tin, cadmium, and metal oxides, as well as many other materials. Coatings produced using ZYP Boron Nitride are also ideal as a braze stop-off and weld spatter release.

Link to the PDF Guide:  Use Areas and Compatibility Guide

Lubricating Qualities

Crystallographically, ZYP Boron Nitride is hexagonal and platy like graphite and offers similar lubrication but is usable to much greater temperatures. For this reason, boron nitride is often referred to as “white graphite.” However, unlike graphite, ZYP Boron Nitride maintains lubricity in vacuum, making it ideal as a high-temperature lubricant for hot-pressing and isothermal forming of superalloys.

5. What Makes Titanium Nitride (TiN) Unique?

Use-Temperatures

ZYP Titanium Nitride coatings are NOT useful in air at temperatures above 350 C, due to the high-tendency of TiN to oxidize.  This oxidation can also cause problems from leaky furnaces [i.e., where air in-leakage can react and cause oxidation and sometimes volatile species also].  In inert/nitrogen atmospheres, TiN is stable to very-high temperatures, with usefulness to above 1900 C [>3450 F].   In vacuum environments, the TiN is usable to around 1600 C and is very stable in contact with carbon/graphite.

Thermal Properties

Titanium Nitride has high thermal conductivity, similar to stainless-steel: 0.069 to 0.018 cal/cm-sec-K (28.9 to 7.53 Watts/m-K) for ‘dense’ TiN from 100 to 1400 C.  Thermal expansion is moderate, typically 8.7 x 10-6/C (25-1000 C).

Electrical Properties

Titanium Nitride is electrically conductive with its electrical-resistivity being 22 x 10-6 ohm-cm at room temperature.  However, ZYP Titanium paints typically have 40-60% porosity after drying and also have binder material; although this reduces the electrical conduction a good amount, the as-applied coating is still a moderate electrical conductor and the only paintable coating we offer with this property.

Chemical Resistance

ZYP Titanium Nitride paints have good chemical resistance … with slags especially, even reportedly being rather stable with the reactive cryolite.

Link to the PDF Guide:  Use Areas and Compatibility Guide

Other Properties of Interest 

ZYP Titanium Nitride “Traycoat” paints are useful for coating graphite trays used for sintering “Hard Metals” which have lower cobalt-level (up to 8% Co).   The TiN stops the diffusion of carbon from the graphite tray into the tungsten-carbide parts.  Also, TiN is stable with Rare-Earth magnet alloys and Molybdenum metal, as well as having good resistance to many molten metals.