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Up Topic Welding Industry / Processes / Chamotte brick for brazing.
- - By xchcui (*) Date 09-14-2016 12:02 Edited 09-15-2016 12:09
Hello.

I would like to use a chamotte brick as a surface for brazing and
i need to choose a size from two option:
1)Thick one-230X115X64(mm).or
2)Thin one-230X115X30(mm).

Which one is preferable?the thinner brick or thicker one?

Thanks in advance.
Parent - - By xchcui (*) Date 09-15-2016 12:06 Edited 09-15-2016 12:09
BTW,chamotte brick is the stone that used for kiln and furnaces.
Attached photo:
Parent - - By xchcui (*) Date 09-15-2016 17:28
Anyone?
Parent - - By Lawrence (*****) Date 09-15-2016 20:17
Welcome to the forum Xchui

How can anybody possibly help you :)  ????

Torch brazing and the bricks will be used as a base?

Oven brazing ? 

How big is the oven?

How hot is the oven?

How long are the heat cycles?

What size are the parts you are brazing?

How long do you want them to last?

How can anybody possibly give you advice when you have shared nothing about the project, the specifications, the requirements of the brazing, the environment they will be in.... Nothing.

Is this for hobby work?

Is this for industrial work?

Tell us something and maybe somebody can help...
Parent - - By xchcui (*) Date 09-17-2016 09:06 Edited 09-17-2016 12:37
Hi Lawrence.

I have noticed that you described a lot of situation by your questions,
But i,actually,wasn't refer to something such complicate.
I would like to braze small items on the chamotte bricks(one or two bricks).
And i just would like to know if it is better to use the thinner brick
or the thicker one.
The question is related to the fact,that those kind of brick has low thermal
conductivity,which help to braze the item on the brick with less heat lost.
So,refer to that fact,what is better to use(in order to have the best efficiency)
thin(230X115X30)chamotte brick or thicker one(230X115X64)?
Parent - - By Lawrence (*****) Date 09-17-2016 14:14
Clearly you want to be secretive and not tell us what you are doing.

I described many different situations... Which one is yours?

Don't want to talk about it?

Neither do I
Parent - - By xchcui (*) Date 09-17-2016 16:50
I really don't understand what do you want from me to add:eek:
What in my question refer to a secret thing?
I mentioned that i would like to braze small items on
that chamotte bricks.
And i would like to know,what is better to use,thick or thin chamotte bricks.
What is so complicate here:confused:
The situation that you mentioned are not related to my question at all.
The issue here is the thermal conductivity aspect.
I will very appreciate any help.
If you can't help,it is ok.
Thanks anyway.
Parent - - By Lawrence (*****) Date 09-17-2016 18:48
Both thick and thin bricks have the same thermal conductivity

The thick bricks are just thicker

The thin bricks are thinner.

Thick ones will probably last longer

Thin ones are easy to carry

Thick ones are probably more expensive

Thin ones are probably cheaper.

You still haven't explained what it is you do other than braze.

Are the bricks for a bloody oven?

Are you just torch brazing by hand and need a flat spot to work on?

Are you doing industrial temperatures and long dwell times?

Are you doing this at home...?

You could be a jeweler?

Are you brazing high temp aircraft blades?

I really don't understand why you cant tell us what you are trying to do.
Parent - - By xchcui (*) Date 09-19-2016 11:59 Edited 09-19-2016 12:05
That what i did,i told you,exactly,what i am trying to do:
I would like to braze small items on 1-2 chamotte bricks
and i focused the question a bout the efficiency of thicker brick vs thinner one
refer to their thermal conductivity.(in order to decrease heating lost when brazing the item).
Refer to your question:i am doing it at home(not often)a it is not for work.
I am just torch brazing by hand and need a flat spot to work on.
It is not an oven,It should be a surface of 1-2 chamotte bricks and the small items should be directly on them to be braze.
What items?any small items.I am not a jeweler,but it should be used to braze items with the same size.it can be small items/parts from tools,machines,cars bicycles etc.that might need to be fixed.I just prepare the area,nothing is broken,right now.
OK.Are you happy now:smile:,though,that information is not needed for answer my question.
Anyway,i made more search in google and i found out,that the densed chamotte bricks are not suitable for my purpose,since they act like an heatsink,they absorb the heat,while i need the opposite situation.
So,i found out,also,that i need the"insulating lightweight fire bricks",which are the actually ones which have the low thermal conductivity(reflect the heat)and might be the ideal surface for the items.
What do you think?
Parent - - By Lawrence (*****) Date 09-19-2016 13:24
",i found out,also,that i need the"insulating lightweight fire bricks",which are the actually ones which have the low thermal conductivity(reflect the heat)and might be the ideal surface for the items."

I agree.
Parent - - By xchcui (*) Date 09-19-2016 18:42 Edited 09-19-2016 18:47
"I agree."
Thats all?:eek:nothing wise to add?:roll:
I was expected for more than just"i agree"
I was expected to learn something from an expert.

Thanks.
Parent - - By Lawrence (*****) Date 09-19-2016 18:48
Xchcui

You are the expert !

You figured everything out, did the research, and made the correct choice.

Go buy your bricks and send us some pictures of your sure to be excellent brazing.
Parent - - By xchcui (*) Date 09-21-2016 12:35
I have checked the densed fire bricks and also the insulating fire bricks.
Is it normal,that when you hold a new insulating fire bricks or move  your hand along the new insulating fire bricks,your hand is covered with a small crumbs of white material from the bricks?
I didn't experience that situation with the densed fire bricks
Parent - - By Lawrence (*****) Date 09-21-2016 13:43
Good question,

I don't know the answer.

All my experience with bricks is with old ones.   I can say the ones I've used were always a little 'crumbly' and had some grains that would come loose on the top... They also would break easily if dropped or chip easily if struck.
Parent - By xchcui (*) Date 09-21-2016 17:47
I suspect that this behavior maybe indicate an old bricks stock,
But i am not sure about that and i don't have other store to compare with.

Thanks.
Up Topic Welding Industry / Processes / Chamotte brick for brazing.

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