ZYP Frequently Asked Questions

Note: These are general questions that are often asked. Aluminum processors - visit our "Solutions for Problems in Molten Aluminum Processing" for more specific information. If you have other specific questions, contact us by phone, FAX, or email.

You may also get some good ideas about many areas and unique uses of our products from our Hot Topics section of the website.

1. What is a ceramic (or high-temperature) coating/paint?

2. How do ceramic paints compare to chemical vapor deposition (CVD) or plasma sprayed coatings?

3. Are ceramic paints temporary or permanent? What is the lifetime?

4. How much material will evolve from the coating and will it hurt (affect) my process?

5. How do I apply these ceramic coatings?

6. How do I dilute these coatings?

7. What thickness do I need to apply?

8. Can I apply these coatings by dipping?

9. What temperature and atmosphere can I use these coatings?

10. If I use an aerosol coating and want to scale up its usage, what can I do?

11. Where can I find the prices for these coatings?

12. How do I order these coatings?

13. Is the coefficient of thermal expansion (CTE) important in matching with the substrate that I am using?

14. What is the range of thermal and electrical conductivity of these coatings?

15. Are these coatings suitable for wear applications?

16. How can porous coatings such as these protect against high-temperature corrosive attack by gases?

17. Do you provide samples of the products?

1. What is a ceramic (or high-temperature) coating/paint?
Our coatings consist of binders/suspension agents, vehicles, and fillers like any commercial house paint. The binders are added to "glue" the main ingredient material to the substrate (which is the surface that you are coating). The binders are typically organic, inorganic, or a mixture of these, depending on the coating. A suspension agent, often the same as the binder, is used to hold the main ingredient in a suspension to keep it from settling out. The vehicle is the liquid that is used for the paint, generally water or a solvent. The filler is the main component of the paint that will be left after the paint is dried: this material is the ingredient that gives the coating its major character and properties. Basically, our coatings are quite like house paint, except that the materials that are added to allow them to act like paint must be designed to evolve as the paint is heated up, while still keeping the main ingredient bonded to the substrate through its high-temperature use.

2. How do ceramic paints compare to chemical vapor deposition (CVD) or plasma sprayed coatings?
Ceramic paints are typically around 50 to 60% dense (or have 40 to 50% porosity) and are applied like house paint. Plasma-sprayed coatings are applied with a VERY high-temperature plasma (over 20000 degrees) and are generally around 85 to 90% density. CVD coatings are 100% dense.

CVD coatings are VERY dependent on the substrate coefficient of thermal expansion (CTE) if they are to be used at high-temperature due to the CVD coatings being fully dense. Plasma-sprayed coatings are less dependent on the substrate CTE, whereas ceramic paint coatings are even less dependent on substrate CTE. The porosity acts as a "shock absorber" for the differences in CTE. Thicknesses: CVD coatings are generally very thin - less than 0.001 inch; plasma-sprayed coatings are typically 0.005 inch to 0.050 inch (although much thicker coatings CAN be applied); ceramic paints are often applied 0.002 to 0.010 inch but can be applied much thicker IF dried thoroughly as they are built up 0.002 to 0.004 inch per application (i.e., by brush).

3. Are ceramic paints temporary or permanent? What is the lifetime?
Ceramic paints can be either temporary or permanent: it depends on the application. Often, the ceramic paints are used in areas where they last for a given time and then require re-coating: the benefits of the ceramic paint justify their re-application, since they solve problems that require their regular use. While nothing is truly permanent, some of our ceramic paints last a very long time at high-temperature (i.e., years). The lifetime, however, is quite dependent on the operating conditions (use temperature, atmosphere, coating thickness, shop practice, and many other factors): thus, the lifetime is different for every area of use and place of use.

4. How much material will evolve from the coating and will it hurt (affect) my process?
Our ceramic coatings are designed with minimal outgassing in mind. Thus, there is always very little material that will evolve from the coatings when they are placed into use. Generally, there is no need to pre-outgass the coatings. They are merely dried and placed into their high-temperature use. The material evolving from the coatings are gases (typically water, carbon dioxide and monoxide and [in some cases] methane or nitrogen oxides); they generally come off in a rather linear fashion from 50 C to 500 C depending on the coating. The slow evolution of the small amount of volatiles generally does not cause any problems - whether the actual use is in an air, inert, or vacuum atmosphere. The overall amount of material evolving is extremely small.

5. How do I apply these ceramic coatings?
Our ceramic coatings are quite easy to apply. Just think of them like house paint. All the ways of applying house paint are OK with these ceramic coatings - brushing and air-spraying being the most common ways. See our Painting Instruction Guide for more details/hints on applying the coatings to metals, ceramics, or graphite substrates.

6. How do I dilute these coatings?
We generally recommend trying the coatings at full strength initially. Some coatings are not designed for dilution and do not perform well if diluted (i.e., Boron Nitride Hardcoat; Coverguard). Most of our coatings can be diluted from 5 to 15% by volume without affecting them strongly. Some of the coatings can be diluted much more: see the individual datasheets for directions on dilution. Water-based coatings (most of our coatings) can be diluted with water, and utensils can be cleaned up using water. Solvent-based coatings can generally be diluted with ethyl alcohol (generally isopropyl alcohol is NOT recommended, since it has a tendency to curdle some coatings) or acetone.

7. What thickness do I need to apply?
The general "rule-of-thumb" is to apply the thinnest coating that you can use. Or, a little is good; a lot is not. The reason for this rule is that thicker coatings have a greater tendency to "mud crack" on drying as well as to spall (come off) on thermal cycling. We recommend thicknesses from 0.002 to 0.010 inch for most of our coatings, with 0.004 to 0.006 inch being a good range to try first.

8. Can I apply these coatings by dipping?
While dipping has been used successfully by some customers, it is not recommended for most of them. Dipping produces a rather thick coating (often over 0.010 inch) which must dry from the outside first. This can lead to the formation of a "shell" layer that is dry to the touch, yet considerable moisture is still in the coating. When these coatings are heated, this moisture can lead to spalling (coming off) of the coating.

9. What temperature and atmosphere can I use these coatings?
Our coatings vary in their specifications for use-temperature and atmosphere (see the individual datasheets). However, we have coatings that can be used to temperatures well over 2000 C. Also, most of our coatings can be used in any atmosphere (air, vacuum, inert): see the individual datasheet to find out specifics.

10. If I use an aerosol coating and want to scale up its usage, what can I do?
We offer "aerosol brushables" of each of the refractory materials that are used in our 13-oz. aerosol cans (yttria, zirconia, alumina, boron nitride, and titanium nitride). These "aerosol brushables" are a bulk form of the material (sold in gallons and also in quarts or pints for some) and allow the coatings to be economically scaled up for brushing, pressurized-air-spraying, etc.

11. Where can I find the prices for these coatings?
The coating prices are on individual datasheets on this website. Call for large-quantity pricing.

12. How do I order these coatings?
The coatings can be ordered online or by telephone (865-482-5717), FAX (865-482-1281) using a company purchase order or by telephone or FAX using American Express, VISA, MasterCard or Discover.

13. Is the coefficient of thermal expansion (CTE) important in matching with the substrate that I am using?
Generally, with paintable ceramic coatings, this is not a very important consideration. The paintable coatings are very "forgiving" for different substrates. This is because of the way the main ingredient is bonded to the substrate and because of the porosity of the coatings. The denser or harder the paintable coating, the more the CTE matching becomes important. Also, the thinner the paintable coating is applied, the more "forgiving" the coating is towards CTE mismatches. Of course, higher CTE main ingredients in our coatings are best for high-CTE substrates (like steel or other high-expansion metals); and, lower CTE main ingredients are best for low-CTE substrates (like ceramics or graphite). Thus, our Sealmet coating works well with most metals. And, Coverguard (silicon carbide-based) works well with most ceramic substrates.

Boron Nitride Lubricoat and Zircwash coatings are very "forgiving" and work well with metals, ceramics, and graphite due to the binders used in those coatings allowing this. The use-temperature is also a consideration: IF the use-temperature is below 600 C, the thermal expansion problems are generally not an issue at all due to the temperature differentials not being great enough to cause spalling. Higher temperatures and drastic thermal changes can cause the CTE mismatch to be a problem with some coatings and substrates.

14. What is the range of thermal and electrical conductivity of these coatings?
The highest thermal conductivity coatings are those of Boron Nitride (which has the same thermal conductivity as steel and is considered VERY high thermal conduction for a ceramic) and silicon carbide (our Coverguard, MW-50, and Type SC or Type SC-1400 Coatings). The lowest thermal conductivity coating is Zircwash - due to zirconium oxide having the lowest thermal conductivity of any oxide.

Coatings with the lowest electrical conductivity are those of Boron Nitride or aluminum oxide (Type A1 or Type A2). The highest electrical conductivity coating is probably our TN-Aerosol (titanium nitride-based). Paintable coatings with electrically conductive main ingredients are still not very good electrical conductors due to the binder material. The binder must glue the main ingredient particles together and glue them to the substrate. The binder is typically an electrically-nonconductive material - thus reducing the electrical conductivity of the overall coating considerably. Therefore, paintable coatings that utilize high-electrical-conductivity main ingredients should only be considered as being barely electrically conductive (i.e., showing very high electrical resistance on a volt-ohmmeter).

15. Are these coatings suitable for wear applications?
Generally, paintable coatings are not good for wear applications. However, there are many applications that are mistakenly thought of as wear - i.e., material is being constantly worn away by molten metal. In the case of molten metal, this is corrosion (not erosion) that is the major concern. Our paintable coatings are very efficient at STOPPING such attack. The molten metal generally does not attack or even wet our coatings; thus, our paintable coatings will greatly improve performance in these areas.

16. How can porous coatings such as these protect against high-temperature corrosive attack by gases?
Our Sealmet coating (designed to protect metals) contains mostly closed porosity and very fine porosity which has a "tortuous path" for the gases to penetrate in order to attack the substrate: thus, the Sealmet is quite effective in protecting the substrates from gaseous attack. Likewise, our Coverguard coating (designed to protect graphite from oxidation) also protects from the air penetrating to the graphite.

17. Do you provide samples of the products?
In general, samples do not provide much information on paintable ceramic coatings. The coatings essentially look and act like house paint in their application, so there is little to gain from use of just a small sample. Considering our R&D product line, these R&D products require very expensive ingredients and thus are only specially produced (to very exacting specifications) when we receive an order: thus, there are none of these products readily available for samples.

Our industrial product line does not work well with small samples -- since the amount of a sample is not enough to run a realistic test. Therefore, we do not typically offer samples. Instead, we recommend that customers order a minimum amount to allow their initial testing of the coatings.