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Lab talk, the good, the bad, and the ugly
Equipment
Zirconia furnace – microwaves
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<blockquote data-quote="tuyere" data-source="post: 371643" data-attributes="member: 26916"><p>I don't really see the point. They're also making a lot of claims that don't stand up to scrutiny. Heating rates are determined by the zirconia, not how fast the machine can heat, so that point is irrelevant. Microwaves don't heat everything evenly like they say, that's just not how this works, the microwaves need to excite the molecules in something that has a high relative permittivity. Zirconia has a low permittivity, similar to glass, and far lower than water or metals, so it is not at all efficient to heat with microwaves. It's actually a notably-bad material, as far as these things go, it is largely microwave-transparent. So it's heating something else- I I'm pretty sure it's heating up a microwave-opaque liner material, you can see a grey liner inside the firebrick; I bet that's silicon carbide, in which case, you still have all the same issues with uneven heating, heat bleed, etc. I would expect it to need the same component replacement and consumable costs, approximately, you don't have heating elements but you have everything else, firebrick and thermocouples and the lot, plus some very specialized parts that will be $$$ when and if they fail, like the magnetron and the heat liner. At least heating elements are relatively cheap and simple components.</p><p>Any sintering oven is functionally one big consumable item, it's unavoidable with the stress of repeated heating and cooling to such extremes, multiple times a day every day. Four years is a good run for a heating element, we replace ours within 2 or maybe 3. Factor for it when considering your operating costs, and look into spare parts availability and price when picking your equipment.</p></blockquote><p></p>
[QUOTE="tuyere, post: 371643, member: 26916"] I don't really see the point. They're also making a lot of claims that don't stand up to scrutiny. Heating rates are determined by the zirconia, not how fast the machine can heat, so that point is irrelevant. Microwaves don't heat everything evenly like they say, that's just not how this works, the microwaves need to excite the molecules in something that has a high relative permittivity. Zirconia has a low permittivity, similar to glass, and far lower than water or metals, so it is not at all efficient to heat with microwaves. It's actually a notably-bad material, as far as these things go, it is largely microwave-transparent. So it's heating something else- I I'm pretty sure it's heating up a microwave-opaque liner material, you can see a grey liner inside the firebrick; I bet that's silicon carbide, in which case, you still have all the same issues with uneven heating, heat bleed, etc. I would expect it to need the same component replacement and consumable costs, approximately, you don't have heating elements but you have everything else, firebrick and thermocouples and the lot, plus some very specialized parts that will be $$$ when and if they fail, like the magnetron and the heat liner. At least heating elements are relatively cheap and simple components. Any sintering oven is functionally one big consumable item, it's unavoidable with the stress of repeated heating and cooling to such extremes, multiple times a day every day. Four years is a good run for a heating element, we replace ours within 2 or maybe 3. Factor for it when considering your operating costs, and look into spare parts availability and price when picking your equipment. [/QUOTE]
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Lab talk, the good, the bad, and the ugly
Equipment
Zirconia furnace – microwaves
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