Sciencemadness Discussion Board

Types of metals for rocket motors

WD40_enjoyer - 12-7-2025 at 11:15

I have for a long time tried to construct different rocket nozzles using different materials like cement, clay, aluminium, copper, stainless steel and lead sponges. But I've had some difficulties with for example: my motors melting or exploding. What do you guys use for designs (ratios and types) and what do you use as materials and what tools are involved.

(Ive experimented with cooled nozzles on small scale (like with co2 or water) and with variating success. Ive thought but not done a heat exchanging nozzle thats cooled by a element in the front of the rocket)

metalresearcher - 12-7-2025 at 11:45

I have no experience with rocket engines (yes, engine, not motor as a motor is electrical), but I bet that Al, Cu or Pb are unsuitable as these metals have a too low melting point to withstand temperatures of the combustion.

WD40_enjoyer - 12-7-2025 at 12:00

1. Motor is not bound to electrical 2. Al is for cost/heat transfer, cu is for better heat transfer and high melting point, pb sponge is for high temp and placeholder for catalysts.

bnull - 12-7-2025 at 12:34

OK, first of all: what propellant are you using? I hope it's not a C-Stoff/T-Stoff sort of combination.

What you need is a refractory alloy. Inconel (nickel-chromium-something else) is a good one, if I'm not mistaken was developed exactly for that kind of application. How much it will cost? No idea.

WD40_enjoyer - 12-7-2025 at 12:40

I am pondering different fuels but right now I'm doing some research for hydrazine (and its derivatives) and an oxidiser like n2o and possible high conc h2o2. Good idea about that alloy, what specs has it and how is it's mechanical properties?

bnull - 12-7-2025 at 13:06

Tish, tish, you'll need to read the literature for that kind of information (Aerospace Materials and Material Technologies, Journal of Aeronautical Materials, that sort of publication). Inconel is not a single alloy, it comes in many specifications and the right one depends on what fuel and oxidant you're using. As far as I know, there's no "one-size-fits-all" alloy.

WD40_enjoyer - 12-7-2025 at 13:58

But for example with n2o and hydrazine at stochimetric amounts what would that consist of? What im getting at is it easy to machine/weld to since if it for example is super difficult to melt/turn down in a lathe I won't be using that but if not then I might depending on price and such factors.

Twospoons - 12-7-2025 at 17:00

The more usual nozzle materials would be fiber reinforced phenolic resin, or graphite. Assuming compacted Bentonite is not working for you. You haven't said how big your rockets are.

[Edited on 13-7-2025 by Twospoons]

WD40_enjoyer - 12-7-2025 at 23:28

I am currently trying different scales since it can very easily get very large when you try to overengineer everything, but my best working prototype is about 5-7cm in diameter.

Fulmen - 13-7-2025 at 06:07

You don't give us anything to work with. What sort of motors? And which propellant? Single use or reusable?

WD40_enjoyer - 13-7-2025 at 06:50

I've said which propellant, they are de laval nozzles and are supposed to be reusable. I've mostly been focusing on the motors themselves and not the entire rocket construction (that means i haven't physically made it fully, but the design exists in Fusion 360).

Twospoons - 13-7-2025 at 14:19

Hmm. In that case I would suggest using replaceable graphite inserts as the hot face in your nozzle. You will get nozzle erosion no matter what you do, so making a small part of the nozzle replaceable would seem sensible. Graphite is easy to obtain, easy to shape, and reasonably priced.

[Edited on 13-7-2025 by Twospoons]

Fulmen - 14-7-2025 at 00:22

Ah yes, I found it after a more thorough reading. But my argument still stands, you're not giving people much to work with. It's hard to judge your level of expertise from your posts. You seem to ask very basic questions while talking about very advanced technologies (liquid fuels). I think you will get better advice if you share a but more about your work up to this point.

WD40_enjoyer - 14-7-2025 at 01:13

Quote: Originally posted by Twospoons  
Hmm. In that case I would suggest using replaceable graphite inserts as the hot face in your nozzle. You will get nozzle erosion no matter what you do, so making a small part of the nozzle replaceable would seem sensible. Graphite is easy to obtain, easy to shape, and reasonably priced.

[Edited on 13-7-2025 by Twospoons]


Hmm seems reasonable to have replaceable parts of the engine. I will look in to it.

WD40_enjoyer - 14-7-2025 at 01:15

Quote: Originally posted by Fulmen  
Ah yes, I found it after a more thorough reading. But my argument still stands, you're not giving people much to work with. It's hard to judge your level of expertise from your posts. You seem to ask very basic questions while talking about very advanced technologies (liquid fuels). I think you will get better advice if you share a but more about your work up to this point.



I'm sorry if I'm not supplying mich information but can you be more specific about the info you want to receive since I'm not fully understanding what it is you want. All I'm asking is for ideas fro materials that can survive corrosion (so i can for example use h2o2) and can withstand high heat. I'm not asking for blueprints nor designs. I'm sorry if I haven't made that clear perfectly!