Question regarding Hardness and Wear Resistance

In summary, the conversation discusses the question of whether a tungsten carbide fountain pen nib would last longer than a traditional iridium + osmium alloy nib. It also explores the relationship between hardness and wear resistance, and the challenges of shaping tungsten carbide into a pen nib. Some alternative materials, such as silicon nitride and BAM (Aluminium - Magnesium Boride), are mentioned as potential options for an indestructible pen nib. However, shaping these materials can be difficult and may require the use of diamond tools.
  • #1
dovidu
22
0
Hello, everyone
i always had this question in mind, and also tried to look for answers on the web,
but alas! i can't seem to find definite answer!

i am currently making a fountainpen nib with a carbide point.

the traditional material for fountainpen tipping is iridium + osmium alloy (iridosmium)

iridosmium moh hardness is roughly 6.5-7.0
tungsten carbide is typically 9.0

also check this out:
-------------------------------------------------------------------------------------------------------------------------------
"The scale is roughly logarithmic,
that is, a material with a hardness of 8 is,
roughly 10 times as hard as another material whose hardness is 7,
which in turn is 10 times as hard as a material whose hardness is 6,
and so on. The minerals chosen by Mohs for this scale are:
10: diamond
9: corundum
8: topaz
7: quartz
6: orthoclase
5: apatite
4: fluorite
3: calcite
2: gypsum
1: talc"
-------------------------------------------------------------------------------------------------------------------------------

the question is...

<1>
this quote in conclusion indicates that,
tungsten carbide is roughly 200-250 times harder than iridomium, as moh scale is "logarithmic"
is this true?

<2>
relationship between hardness and wear resistance??
for example, a iridomium tipped nib on paper will last roughy 10 years...
>>>> how about a tungsten carbide tipped nib on paper? 10 X 250 years?
 
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  • #2
Hardness is an intrinsic property of a material (having to do with the molecular bonding) whereas "wear resistant" is more subjective and can depend on the answer to the question "resistant to wear from what material?"
 
  • #3
How would you form it into the tip shape?

Do a search on "machining tungsten carbide" and read some of the answers. It sounds like you want to pre-form a tip made out of other material, then sinter the tungsten carbide layer as the new surface. Ordinary grinders and milling tools other than diamond, are too soft to machine tungsten carbide.

I was surprised when searching "tungsten carbide tip" to find pens with such tips. But they were not ink pens, but rather engraving/etching scribes.

I think tungsten carbide is pretty rough, whereas a pen nib needs to be smooth to "glide" over the paper surface.

Anyhow, it sounds like a good challenge. Good luck.
 
  • #4
i have already succeeded making such carbide point nib.

the relevant question here is:

low much longer would it last, compared to traditional iridosmium point nibs

writing material is paper
 
  • #5
That's really hard to say.

How do you define end of life?

How does the coefficient of friction compare tungsten versus traditional?

You would need data on abrasion resistance of tungsten versus traditional. That is related to but not identical to hardness.

You may find some data here https://en.wikipedia.org/wiki/CRC_Handbook_of_Chemistry_and_Physics
 
  • #6
anorlunda said:
How would you form it into the tip shape?

Do a search on "machining tungsten carbide" and read some of the answers. It sounds like you want to pre-form a tip made out of other material, then sinter the tungsten carbide layer as the new surface. Ordinary grinders and milling tools other than diamond, are too soft to machine tungsten carbide.

I was surprised when searching "tungsten carbide tip" to find pens with such tips. But they were not ink pens, but rather engraving/etching scribes.

I think tungsten carbide is pretty rough, whereas a pen nib needs to be smooth to "glide" over the paper surface.

Anyhow, it sounds like a good challenge. Good luck.
You are mistaken.
As a part of my engineering hobby I do *turn* on odd occasion tungsten carbide.
Modern turning tool manufacturers, eg Sumitomo Electric but also some cheap chinese suppliers are producing special *cubic boron nitride* tipped inserts good enough for the task.
For grinding Tungsten carbide you can use diamond, cubic boron nitride or cheap silicon carbide grinding wheels.
 
  • #7
@dovidu,
If your objection is to manufacture *indestructible tip for fountain pen*, you might consider 2 materials.
1. Silicon nitride tip or even better:
2. BAM (Aluminium - Magnesium Boride) tip.
The latter has a hardness very close to diamond *and* the lowest friction coefficient of any earthly material known (about twice lower than teflon). On the top of it excellent chemical resistance and it is easy to wet with water or organic based ink.
It is pig to shape even with diamond laps or grinding wheels. Even NASA complains.
 
  • #8
unfortunately its impossible to make 0.05mm slit for such material...
even carbide has to be done with diamond
Martin0001 said:
@dovidu,
If your objection is to manufacture *indestructible tip for fountain pen*, you might consider 2 materials.
1. Silicon nitride tip or even better:
2. BAM (Aluminium - Magnesium Boride) tip.
The latter has a hardness very close to diamond *and* the lowest friction coefficient of any earthly material known (about twice lower than teflon). On the top of it excellent chemical resistance and it is easy to wet with water or organic based ink.
It is pig to shape even with diamond laps or grinding wheels. Even NASA complains.
 
  • #9
dovidu said:
unfortunately its impossible to make 0.05mm slit for such material...
even carbide has to be done with diamond
It would be possible on BAM with electric spark erosion technology.
 
  • #10
Martin0001 said:
It would be possible on BAM with electric spark erosion technology.
could be but not the slitting thickness of 0.05mm
 
  • #12
phinds said:
Hardness is an intrinsic property of a material (having to do with the molecular bonding) whereas "wear resistant" is more subjective and can depend on the answer to the question "resistant to wear from what material?"
How true. Soft 'white metal' bearings will wear down a hard steel crankshaft.
 
  • #13
sophiecentaur said:
How true. Soft 'white metal' bearings will wear down a hard steel crankshaft.
I have a lathe with plain bearings. I had to replace bearings one time but not a journal.
Bearings are becoming harmful usually if there is inadeuate lubrication or if hard particles, eg dust from nearby grinder, finds its way into bearing surfaces.
Then process known as lapping will take care of journal, eg destroy it by galling.
Under normal working conditions you will replace bearings several times before replacement or regrinding of journal is called upon.
 
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  • #14
phinds said:
Hardness is an intrinsic property of a material (having to do with the molecular bonding) whereas "wear resistant" is more subjective and can depend on the answer to the question "resistant to wear from what material?"

Very true. My ex employer found out the hard way that Nylatron is very wear resistant when running against steel, but not at all wear resistant against paper.
 
  • #15
the post is becoming very off topic!

so, nobody has clue? whether moh scale is logarithmic?

what's the hardness difference between 7 vs 9 ? 100 times??

does anyone know wear resistance of osmium vs tungsten carbide on paper?

it doesn't have to be exact
 
  • #16
I am not aware of any published information on wear resistance of materials against paper. I do know that CPM10V is a popular alloy for slitter knives. I once was told that if CPM10V does not have sufficient wear resistance, then you need to use a carbide. That was before CPM15V came out.

Also, hardness alone does not predict wear resistance. Crucible makes a series of knife steels that are far more wear resistant than simple carbon steels at the same hardness. Here is a wear resistance comparison of some tool steels: http://www.crucible.com/eselector/general/generalpart6a.html.
 

1. What is hardness and wear resistance?

Hardness is the ability of a material to resist indentation or penetration. It is measured on a scale called the Rockwell scale, with higher numbers indicating a greater resistance to indentation. Wear resistance, on the other hand, is the ability of a material to resist wear and tear from repeated contact with another surface.

2. What factors affect the hardness and wear resistance of a material?

There are several factors that can affect the hardness and wear resistance of a material, including its chemical composition, microstructure, and processing methods. For example, adding certain elements to a metal alloy can increase its hardness, while heat treatment can improve its wear resistance.

3. How are hardness and wear resistance measured?

Hardness is typically measured using specialized instruments such as a Rockwell or Vickers hardness tester. Wear resistance can be measured using a pin-on-disk test, where a material is rubbed against another surface and the amount of wear is measured. Both of these measurements provide numerical values that indicate the material's hardness and wear resistance.

4. Why is hardness and wear resistance important?

Hardness and wear resistance are important properties for materials used in various industries, including manufacturing, construction, and engineering. Materials with high hardness and wear resistance are more durable and can withstand heavy use, reducing the need for frequent replacements and maintenance.

5. How can hardness and wear resistance be improved?

There are various ways to improve the hardness and wear resistance of a material, such as alloying, heat treatment, and surface treatments like coating or nitriding. The specific method used will depend on the type of material and the desired properties. Additionally, choosing a material with inherently high hardness and wear resistance can also be beneficial in certain applications.

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