Key Questions to Ask When Ordering Reactive Magnesium Oxide Supplier

Magnesium Oxide Packing for Cartridge Heaters and Thermocouple Assemblies

Magnesium Oxide Packing for Cartridge Heaters and Thermocouple Assemblies

Magnesium Oxide powder serves as a standard packing material for cartridge heaters and thermocouple assemblies. I intended to acquire a cartridge heater for a CuCl2 etch tank, deciding to construct one using glass. While searching for MgO, I found it somewhat costlier than expected. Here are my preliminary findings, and feel free to add any sources you might be aware of.

Sources for Magnesium Oxide

The most common source is your local vitamin and supplement store, where the powder form is sold. Prices range from USD 6 to 10 per pound for quantities between 1/2 and 2 pounds.

Another potential source is ceramic supply houses, although magnesium oxide is not universally available there. It’s used in glaze formulation, but most formulators prefer magnesium carbonate, as seen in dolomite. One vendor sells 5 lbs for USD 13.

An assay supplier offers 10 lbs for USD 23 and 55 lbs for USD 56.

Like you, I also faced challenges in locating MgO. I was considering an immersion heater for my lead dioxide plating experiments and found it to be less common. Your sources are cheaper than mine.

Have you thought about buying one off the shelf? Industrial cartridge heaters are available and affordable on eBay and from surplus sources. For around $20, you can get a 500 to 1000-watt heater encased in stainless steel or inconel. Higher wattage densities likely have inconel sheaths.

For the premium option, Process Technology offers PTFE-encased immersion heaters. L-shaped heaters are optimal for heating smaller tanks. Another eBay source, user SurplusPlating, sells these.

Two days ago, I made a purchase. Even if you don’t need PTFE for your current project, it’s beneficial for future unknown uses.

Paired with a $30 Chinese PID temperature controller, these heaters can maintain a precision of +/- 1 degree all day. Though I appreciate DIY, the metallic-sheathed cartridge heaters are inexpensive and worth considering.

What is your plan for creating a cartridge heater? Are there any DIY resources available online?

If you're open to an extra step, you can convert MgCO3 or Mg(OH)2 (easily made from MgSO4) in a furnace to MgO.

For more information, please visit our website.

DIY Cartridge Heater Construction

Creating a cartridge heater involves wrapping a coil of wire, placing it in a tube, packing it with MgO, and compacting the filler. The challenge lies in keeping the coil insulated to avoid shorts. Here are the steps:

• Use a threaded rod as a core form to wrap the resistance wire and hold it centered in the tube.
• After wrapping the wire and assembling the jig, pack the cavity with MgO.
• Remove the core form carefully, leaving a void, and fill it with MgO.
• Compact the filler using a tamping block and seal the top with casting resin.

This method should work for ordinary wire gauges (18-30 AWG). For finer wires, the success is less certain. Another approach is using a hollow tube as the core form.

With this setup, achieving adequate heat density is not an issue:

• 1000W from 120V mains requires around 20 inches of 30-gauge Kanthal A-1 wire.
• Nichrome wire would be about 1.5 times this length.
• Wrapping around a 1/2-13 NC thread results in slightly less than an inch of winding.

(Note: Be aware of aspects like "maximum surface load" of heating wires to prevent burnout.)

Further Insights on Heating Elements

Regarding heating theory, you could wrap a thin sheet of glass cloth or similar material between the coil and tube wall to prevent shorts. Alternatively, threading the resistance wire through a PTFE tube and filling the void with high-temp silicone oil might work, provided the wire’s temperature stays below PTFE’s working limits.

For warming a tank to 90C, a coil of nichrome in a U-shaped glass tube filled with air suffices, though it may not be quick. Use a variac as input.

For achieving 1000W from an inch coil of Kantal, ensure a steady air flow to prevent burnout.

Explore the Meishen Product Page for more.

Utilizing Mg Metal as an Oxygen Getter

If Mg’s reactivity is beneficial for holding oxygen, consider using Mg powder as an oxygen getter inside the cartridge heater, similar to getters in vacuum tubes. Some considerations:

• Utilize Mg powder for its high surface area.
• Perform a burn-in period to oxidize Mg without combustion.
• Pressurize the cartridge before sealing to ensure proper oxygen removal.
• Minimize Mg metal usage to a slight molar excess of the gas present between the fill material.

For DIY methods, calcining Mg(OH)2 into MgO from MgSO4 and NaOH can be costly and labor-intensive, but it is an option. Blackboard chalk and white powder chalk refills are cheaper alternatives for raw materials.

Browse Kanthal Heating Alloys Handbook for details on wire surface loadings and configurations. For heating elements, configurations, and practical ratings, consider a cartridge 4" long by 3/4" diameter at specific load ratings for feasibility.

Ultimately, achieving the right balance of geometry, material costs, and manufacturing stress will ensure an efficient DIY cartridge heater for various projects.

Need more information on Reactive Magnesium Oxide Supplier? Feel free to contact us.