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What is the feasibility of using graphite, particularly variants that are easy and affordable to acquire, in a combustion chamber, nozzle and bell as well as nozzle extension? Does it need reinforcement with some lighter material? How does it ablate, or for that matter, does it ablate at all or does it oxidize, and if so what can be done to prevent oxidation.`Does it work as higher pressure or is it just limited to low-pressure amateur engines as I've seen previously (was unable to find link, may have been taken down as the website hadn't been updated in years since I last looked)?

As well as this, how could such a technique be implemented in an amateur rocket engine with limited manufacturing methods?

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    $\begingroup$ Likely massively depends on heat, chemical makeup, and flow velocity $\endgroup$ – ikrase Sep 16 '20 at 6:03
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    $\begingroup$ I've adjusted the wording of your question a bit, can you double check that the meaning is preserved? $\endgroup$ – uhoh Sep 16 '20 at 12:00
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    $\begingroup$ I strongly doubt that the ablation will be anything like uniform. More likely there'll be 'hot spots,' leading to your own personal Challenger disaster. $\endgroup$ – Carl Witthoft Sep 16 '20 at 12:15
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    $\begingroup$ I think you should avoid graphite in the combustion chamber (too much oxygen here, cooling jacket for this part is simple anyway), and run fuel rich to make sure that no oxygen remains to burn the graphite in the nozzle. Just my guess. Also, are you sure that 3:1 will get you enough efficiency? $\endgroup$ – Abdullah Sep 16 '20 at 15:29
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    $\begingroup$ Let's edit it to make it on-topic. $\endgroup$ – Abdullah Sep 16 '20 at 17:27
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The ablation of high-purity graphite in oxygen and air atmospheres was studied in the 1000–1400°C temperature range,Very fast ablation rates were observed. The concern is the graphite wouldn't ablate equally overall, running the risk of uneven heating from combustion products.

Also, graphite is pretty heavy substance.

Abstract

The ablation of high-purity graphite in oxygen and air atmospheres was studied in the 1000–1400°C temperature range, gas pressures of 2–19 torr and flow rates of 7.6×1018 to 3.6×1020 atoms/sec. Gas diffusion effects were eliminated by the use of small samples and fast flow-rates. Very fast ablation rates were observed. The kinetic data are best fitted to a model based on mobile adsorption as the rate limiting step with a heat of activation of 39,000 cal/mole.

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    $\begingroup$ Do you have a source for this information? $\endgroup$ – Organic Marble Sep 16 '20 at 20:23
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    $\begingroup$ Scientific book/journal :Carbon Volume 1, Issue 4 Pages 413-545 (July 1964) $\endgroup$ – LazyReader Sep 16 '20 at 20:25
  • $\begingroup$ I've moved that back into your post. In Stack Exchange comments are considered temporary and can be deleted at any time without warning, so the only way that we can ensure that future readers will have access to the information is to put it in the post itself, not in comments. $\endgroup$ – uhoh Sep 17 '20 at 6:31
  • $\begingroup$ not paywalled, and possibly helpful but I'm not sure. If you think this supports your answer feel free to include it as well in the answer: Degradation of carbon-based materials under ablative conditions produced by a high enthalpy plasma jet $\endgroup$ – uhoh Sep 17 '20 at 6:33

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