Need Help in nano-WC-Co-Cr HVOF Coating
07-22-2014, 04:58 PM,
#1
Rolleyes  Need Help in nano-WC-Co-Cr HVOF Coating
I have deposited nanostructured WC-Co-Cr coatings with two different parameter sets using JP-5000 gun. After doing the XRD and semi-quantitative analysis one coating (A) consists of phases like WC (90.34%), W(4.20%), and WC1-x (5.46%) whereas other coating (B) has only two phases WC(90.38%) and Co3W3C(9.62%). Although both coatings have almost same amount of retained carbide but there is a noticeable difference in properties. Coating A has micro-hardness = 1200 HV300, porosity =1.91%, as-sprayed roughness = 3.20 Ra; whereas Coating (B) has micro-hardness = 1598 HV300, porosity = 1.02 %. Also the performance of Coating B in wear testing is better as compared to coating A.

So my question is related to the effect of different phases on properties and wear performance of nano-WC-CoCr coatings. What is the effect of W and WC1-x on the properties and performance as compared to phase Co3W3C.

Please give some good infromation about phase Co3W3C, it is also known as M6 phase.

Thanks in advance
Reply
08-16-2014, 03:28 PM,
#2
RE: Need Help in nano-WC-Co-Cr HVOF Coating
Hi Lalit

A few questions first:

Is your powder a 86WC/10Co/4Cr?
What is the phase make up from this powder?

This is a complex topic and you also need to consider the effect of factors like porosity/hardness on coating performance as well as the different phases.

Generally, the best coatings will mimic the starting powder composition and phases, showing the least interaction between the WC and matrix phases. Nano-structured powders will be far more sensitive to decarburisation and formation of less desirable metastable phases than the micro-structured powders.

The way to go with spraying these powders is to increase particle velocity while reducing particle temperature.
Reply
09-26-2014, 01:31 PM,
#3
RE: Need Help in nano-WC-Co-Cr HVOF Coating
(08-16-2014, 03:28 PM)Gordon Wrote: Hi Lalit

A few questions first:

Is your powder a 86WC/10Co/4Cr?
What is the phase make up from this powder?

This is a complex topic and you also need to consider the effect of factors like porosity/hardness on coating performance as well as the different phases.

Generally, the best coatings will mimic the starting powder composition and phases, showing the least interaction between the WC and matrix phases. Nano-structured powders will be far more sensitive to decarburisation and formation of less desirable metastable phases than the micro-structured powders.

The way to go with spraying these powders is to increase particle velocity while reducing particle temperature.

Dear Gordon Sir,

Yes coating powder is 86WC/10Co/4Cr, with primary WC size is 50-200nm. The coatings have been deposited with optimized process parameters. Both the coatings are actually deposited with different spray parameters sets under optimization study. Starting powder contain only WC phase and no other W2C, W, Co3W3C or any phase is identified. I have also read in one paper of Bouaricha and Marple, 2004 that formation of Co3W3C is good for the coating if W phase is not present. The parameters have been obtained after inflight particle diagnostic study where powder particles have temperature in the range of 1700-1900 degree celcius and velocity is 600-750 m/s. I have an idea about decarburization but I am interested in knowing the effect of generation of Co3W3C phase in nano-coating. Means it is really true that if only Co3W3C is present in small quantity along with WC phase then it will be good for coating properties and wear perfromance.
Reply




Possibly Related Threads…
Thread Author Replies Views Last Post
Lightning How to spray nano-hydroxyapatite (HAp) powder Lalit 6 4,474 12-30-2014, 06:38 PM
Last Post: Met.Eng.
  nano coating on glass teknomas 2 4,545 06-30-2012, 08:48 AM
Last Post: flame
  Nano Coatings ARIKAN 5 7,649 12-16-2007, 07:36 AM
Last Post: drramc



Users browsing this thread: 1 Guest(s)





Surface Engineering Forum Sponsor - Alphatek Hyperformance Coatings Ltd