Corroded aluminium alloy sheaves

[Fr J Hackett]

I did a bit of research and there are over 100 known Manganese/Aluminium silicate minerals - and quite a few are pretty colours (mainly pink or orange)! So maybe there's hope for a nicely coloured result from oxidizing aluminium with permanganate solutions. Maybe add sodium silicate to the mix?

Manganese is surprisingly common in rocks!

I think they are as are the manganese aluminium silicon alloys formed in the melt phase from the liquified solids, the phase diagrams would be interesting and the aluminium manganese silicates are from memory glasses as in gem stones.
Food for thought.

 

[AntarcticPilot]

I think they are as are the manganese aluminium silicon alloys formed in the melt phase from the liquified solids, the phase diagrams would be interesting and the aluminium manganese silicates are from memory glasses as in gem stones.
Food for thought.

They wouldn't be glass - they'd be crystalline, like almost all gemstones - the only common exception is obsidian. I'm a geologist with an interest in mineralogy. And I doubt that they would form under conditions that we'd want to be near! Basically they're complex silicates; as you say, the phase diagrams are interesting and complex. We usually express them in terms of ratios of oxides rather than elemental proportions.

 

[Fr J Hackett]

They wouldn't be glass - they'd be crystalline, like almost all gemstones - the only common exception is obsidian. I'm a geologist with an interest in mineralogy. And I doubt that they would form under conditions that we'd want to be near! Basically they're complex silicates; as you say, the phase diagrams are interesting and complex. We usually express them in terms of ratios of oxides rather than elemental proportions.

I was digging into memory of materials science lectures of over 50 years ago so the definitions of glasses and crystals were a consideration I ignored

 

[AntarcticPilot]

I was digging into memory of materials science lectures of over 50 years ago so the definitions of glasses and crystals were a consideration I ignored

Phase diagrams and crystallography are pretty much ground into me. Not sure how much I can remember, but it's because of crystallography that my spherical trigonometry is good! And yes, there is a relationship.

 

[Fr J Hackett]

Phase diagrams and crystallography are pretty much ground into me. Not sure how much I can remember, but it's because of crystallography that my spherical trigonometry is good! And yes, there is a relationship.

Stuff of reoccurring nightmares and explains my phobia of computer programming. As a final year undergraduate one of my projects was trying to write a program to elucidate a crystal structure From some X Ray Diffraction plates. I am going to have to go and lie down just thinking about it and all the punched cards that went with it.

 

[AntarcticPilot]

Stuff of reoccurring nightmares and explains my phobia of computer programming. As a final year undergraduate one of my projects was trying to write a program to elucidate a crystal structure From some X Ray Diffraction plates. I am going to have to go and lie down just thinking about it and all the punched cards that went with it.

I had to do it by hand in my first year! Computers weren't everyday tools then.

 

[Neeves]

I had to do it by hand in my first year! Computers weren't everyday tools then.

Stuff of reoccurring nightmares and explains my phobia of computer programming. As a final year undergraduate one of my projects was trying to write a program to elucidate a crystal structure From some X Ray Diffraction plates. I am going to have to go and lie down just thinking about it and all the punched cards that went with it.

Surely you used adding machines - or you are very very old. Single computers then filled whole rooms - and were less powerful that a cheap laptop today.

I occasionally wonder what happened to all that kit, XRD, XRF - that again filled rooms.

Jonathan

 

[Fr J Hackett]

Surely you used adding machines - or you are very very old. Single computers then filled whole rooms - and were less powerful that a cheap laptop today.

I occasionally wonder what happened to all that kit, XRD, XRF - that again filled rooms.

Jonathan

Yup 53 yers ago, hence the punch cards. I did have a Sinclair programable calculator 31 or 39 lines if I remember correctly used it to calculate the fuel burn on a moon lander, used to crash a lot. I think it was a Sinclair Cambridge programmable bought in kit form £29.00 not an inconsiderable sum.

 

[AntarcticPilot]

Surely you used adding machines - or you are very very old. Single computers then filled whole rooms - and were less powerful that a cheap laptop today.

I occasionally wonder what happened to all that kit, XRD, XRF - that again filled rooms.

Jonathan

Even adding machines were beyond the ken (and pocket!) of an impecunious undergraduate!

Somewhere around I have a unit of core memory from a machine of that era (Titan). It was decommissioned when I returned to academia in the 1980s.

 

[Ian_Edwards]

A slight thread drift.
Would industrial ascetic acid work instead of citric acid?
Would it dissolve the corrosion you get with Aluminum in salt water?
I have some 27% ascetic acid I used for clean up after using epoxy resin. Before it cures of course.

 

[Fr J Hackett]

A slight thread drift.
Would industrial ascetic acid work instead of citric acid?
Would it dissolve the corrosion you get with Aluminum in salt water?
I have some 27% ascetic acid I used for clean up after using epoxy resin. Before it cures of course.

Are you mixing up acetic acid with acetone, as I find it odd that anyone would use acetic acid to clean up epoxy resin.
But if it's acetic acid yes it will work, if it's acetone it won't.

Acetic acid will smell like vinegar.

 

[Refueler]

My sheaves were corroded ... I cleaned them up .... checked the amount of play .. yes there was quite a bit of play .. but the halyards are larger than the play amount .. so its unlikely for halyard to be affected .. I put them back in mast - and all fine ... halyards run nice and free.

I could if necessary ask my mate to create new in Dural (Duraluminium - aerospace alloy) ... which would literally last longer than boat !!

The main area to consider - is the surface the rope runs on .. make sure its smooth and no edges to wear the rope. Second that the bushing is reasonable for the 'pin' its fixed and using as axle.

 

[Lee Shaw]

My sheaves were corroded ... I cleaned them up .... checked the amount of play .. yes there was quite a bit of play .. but the halyards are larger than the play amount .. so its unlikely for halyard to be affected .. I put them back in mast - and all fine ... halyards run nice and free.

I could if necessary ask my mate to create new in Dural (Duraluminium - aerospace alloy) ... which would literally last longer than boat !!

The main area to consider - is the surface the rope runs on .. make sure its smooth and no edges to wear the rope. Second that the bushing is reasonable for the 'pin' its fixed and using as axle.

Dural is an aluminium-copper alloy that has poor resistance to corrosion under marine conditions. I'm sure there are other aluminium alloys, preferably not alloyed with copper, that would work, or non-metallic sheaves which seem to be fairly common.

 

[Ian_Edwards]

Are you mixing up acetic acid with acetone, as I find it odd that anyone would use acetic acid to clean up epoxy resin.
But if it's acetic acid yes it will work, if it's acetone it won't.

Acetic acid will smell like vinegar

Yes,
From what I read it inhibits part B, and stops the epoxy curing, and it does work on un-cured epoxy.
If you immerse a brush or roller in vinegar before the epoxy cures you can effectively wash it off.
It's much safer than using acetone or IPA, although the workshop may smell like a chippy.
Goggle it.

 

[Refueler]

Dural is an aluminium-copper alloy that has poor resistance to corrosion under marine conditions. I'm sure there are other aluminium alloys, preferably not alloyed with copper, that would work, or non-metallic sheaves which seem to be fairly common.

With all respect - I defer to Metal Master in all matters such as this.

I actually have one sheave made by him at base of mast that today still looks same as day he made it 5yrs ago ...

Theory and actual - often differ.

 

[Fr J Hackett]

Yes,
From what I read it inhibits part B, and stops the epoxy curing, and it does work on un-cured epoxy.
If you immerse a brush or roller in vinegar before the epoxy cures you can effectively wash it off.
It's much safer than using acetone or IPA, although the workshop may smell like a chippy.
Goggle it.

well never knew that.

 

[vyv_cox]

Many years ago when I rode a motorbike and read motorbike magazines, a regular feature was 'Boil your head!' Cylinder heads that had suffered years of exposure to all that British roads could throw at them could be restored to pristine condition by boiling in washing soda, sodium carbonate solution.

 

[Refueler]

Many years ago when I rode a motorbike and read motorbike magazines, a regular feature was 'Boil your head!' Cylinder heads that had suffered years of exposure to all that British roads could throw at them could be restored to pristine condition by boiling in washing soda, sodium carbonate solution.

Even though I was a Lambretta rider ... that was well known in those days ....

Blimey - have you seen prices for Lambo's now ?? My TV200 bored out to 227cc which later raced for RN Hampshire only cost me 50 quid back in 1973 ... that same Lambo if still around would be thousands !! I read that they they are prime targets for thieves now !

 

[Lee Shaw]

With all respect - I defer to Metal Master in all matters such as this.

I actually have one sheave made by him at base of mast that today still looks same as day he made it 5yrs ago ...

Theory and actual - often differ.

"I could if necessary ask my mate to create new in Dural (Duraluminium - aerospace alloy) ... which would literally last longer than boat !!"

You could be on to something here if marine engineers have been wrong to avoid aluminium-copper alloys and metallurgical knowledge from the 1930's to date is incorrect. For the time being though, I won't be specifying aluminium-copper alloy for sheaves or any other component on my boat.

 

[Refueler]

"I could if necessary ask my mate to create new in Dural (Duraluminium - aerospace alloy) ... which would literally last longer than boat !!"

You could be on to something here if marine engineers have been wrong to avoid aluminium-copper alloys and metallurgical knowledge from the 1930's to date is incorrect. For the time being though, I won't be specifying aluminium-copper alloy for sheaves or any other component on my boat.

Fair enough ... all I said is that I defer to a person who makes his living very successfully in Metal Fabrication. So much so in fact that he fabricates various articles for Swedish Aerospace ... as well as many other clients.
Its possible that I mixed up materials he used with another ...