Below are the 8 most recent journal entries recorded in thermal_spray's LiveJournal:

Tuesday, February 13th, 2007
12:08 am	Long Overdye Update I won't even try to go over the stuff I have done in the last few months. It will suffice to say that: 1. We have yttria and XP1104 coatings 2. We now are working with a Ni-5%Al powder, and don't have coatings yet. 3. All coatings created have been fed externally. 4. We have managed to get some coatings with both hoppers on, though our first attempt at a volumetric 50/50 Yttria/Ni-5%Al turned out to be mostly yttria. We will work on that later. 5. My abstract was accepted to ITSC'07 in Beijing, and I am working on the paperwork now. Today, I gave Matt a tour of the lab and he'll soon be coming in and helping us out. Right now, it's mostly Nick, Michael, Matt and I running things, though Kyle and Nathan stop in occasionally. I also have some thermal analysis (DTA/TGA and dilatometry) to do soon as well. (5 Comments |Comment on this)
Friday, November 3rd, 2006
7:41 am	A list of updates 10/24/06 1. We finally got some argon, and it's in larger tanks! 2. Put in a lower shelf in the thermal analysis room. 3. Sent Progress Report to Dr. Hirschfeld for review 10/20/06 4. Computer arrived from TigerDirect 5. Dilatometer repair: both thermocouples (furnace and sample) were broken. I replaced the sample thermocouple and started to replace the furnace one when I found that the element was broken as well. Linseis is going to send out a technician. 6. Contacted MHI about elements, but they require a minimum order of 12. 10/25/06 1. Finished yttria DOE, however, the last four runs had no powder feed. I will redo these soon. 10/26/06 1. Reassembled second hopper. 2. Set up computer in thermal spray lab. I am temporarily borrowing the monitor from the thermal analysis room, because the old monitor does not work with this computer. 3. Moved DTA controller to the new shelf. 10/27/06 1. Send element dimensions to Linseis. Capillary length = 26cm, flange diameter = 36mm. 10/30/06 1. Repeat samples 5-8 on Yttria DOE. They will be listed in the excel file as soon as I upload it. This will continue until 11/06/06 2. Sent in funding proposal to the graduate student association. 3. Fixed the hopper, heater works, power switch facing correct direction, etc. 4. Replaced wire between wires 34 and 10 in the control box. This one broke and would not start the gases on the 30th. Fixing the wire fixed the problem. 10/31/06 1. Argon regulator ordered from VWR. 2. Labview set up on the thermal spray computer. 3. Hoppers had 50V between chassis. I added a grounding wire between them and fixed a pinched wire in one of the hoppers. 11/1/06 1. Ran sample 8 again. Powder hose was loose at the gun on one, and then the hopper clogged for the other. 11/2/06 1. Moved dilatometer control to shelf. 2. Set up computer in thermal analysis room. (3 Comments |Comment on this)
Thursday, October 19th, 2006
7:42 pm	Last weekish October 11, 2006 a. Six successful nickel runs, unfortunately we are only averaging 6-10% efficiency on our coatings. Nathan helped with the first five, Mike with the last nickel coating. b. One failed yttria run. No powder flow, though the plume turned bright red. Mike helped with this attempt as well. Hopefully I'll upload the table of all spray runs shortly. October 12, 2006 Today was busy school-wise, so I only worked on the Excel spray file. October 13, 2006 We had an 8am meeting this morning. From it, I learned we should: a. Aim for 50-60% efficiency, as this is pretty standard. b. Buy a computer for the DTA and one for controlling the hoppers. c. Check the pressure balance line on the hopper which is not feeding yttria. Also try vacuum drying yttria and adding 5 vol% fumed silica to see if that will keep it dry enough to feed. d. I will propose my thesis in January I ordered the computers today from Tiger Direct. October 16, 2006 Today, I disassembled the hopper we were using for yttria. I could not get the powder wheel off and had to completely disassemble the hopper. I ended up taking the motor out. Ultimately, to separate the wheel from the shaft, I had to drive the wheel around with a punch and then beat the shaft out with a rubber mallet, as the bottom plate was held in a vice. The wheel is neither flat nor useable. Someone at some point tried to pry the wheel off with a screwdriver or some other unsuitable pry bar and bent it out of flat. This allowed powder to get behind the wheel and help bind it to the motor shaft. We have ordered a new wheel from Thermach, as well as another hopper kit, which has all the O-rings and felts, which should be kept only for one powder. I ordered a flat screen monitor for the DTA computer as well. October 17, 2006 a. We had two successful yttria runs this morning! The coatings aren't thick, but using a flat powder wheel, vacuum drying, and 10 SLPM Ar for carrier gas seemed to work. I'll add it to the spreadsheet and try to upload it soon. b. The rest of the dy was spent installing the shelves for the thermal analysis room. I have put the controllers and power supplies up on the shelves, freeing up space on the counter for sample preparation. I don't think everything is hooked up properly yet, but I will work on that some more this week. October 18, 2006 Busy class day, I got nothing done. October 19, 2006 a. I have set up a factorial experiment to investiate the effects of current, helium flow rate and argon flow rate on the effiency and weight gain on yttria samples. There will be 8 experiments, and I did one this morning, before running out of argon. b. Ordered more argon. c. Updated this journal finally d. Started assembling dilatometer again. I forget a few steps, so I am going to wait until Scott is back in town before finishing. (1 Comment |Comment on this)
Wednesday, October 11th, 2006
8:51 am	Last Few Days October 9, 2006 1. Two failed nickel (XP1104) runs: a. 50SLPM Ar, 10 SLPM He, 7 SLPM Ar, 850A for all three b. 1.5RPM, tamper, no heat, Thermach hose c. 100mm standoff, 150mm/s, step size 4, 5 passes d. Standard sample prep e. NO POWDER FLOW on either run 2. Switched to tygon powder hose: a. start: 6:25:07am, powder: 6:29:57am, end: 6:33:21am b. 50SLPM Ar, 10 SLPM He, 7 SLPM Ar, 850A for all three c. 1.5RPM, tamper, no heat, Tygon hose d. 100mm standoff, 150mm/s, step size 4, 10 passes e. Standard sample prep f. Thickness change: 3.1mm-3.8mm, 0.7mm difference g. Weight change: 20.81g-25.94g, 5.13g difference 3. Yttria drying experiment 11:00am -> 12.34g 12:00pm -> 12.68g 2:00pm -> 12.76g 4. Nathan ran controls, I ran the hoppers and manipulator. The thermach hose was clogged with WET nickel powder. This could be a function of it being a really wet and nasty morning, or maybe from cleaning the hopper and not disconnecting the powder hose (but maybe I did disconnect it, I can't remember). October 10, 2006 1. Four yttria runs: No powder flow for any of them, even using tygon hose. Plume was cherry red as noted in other experiments. Mike ran the hoppers and manipulator, and I ran controls. 2. Second powder line connected. We need a better Argon regulator, as the only one we have only goes to 15psi on the line side, not enough to get flow through the system. There was some leaking around the pressure sensor and critical orifice. These leaks were repaired by adding teflon tape to the threads of the connections, but further leak testing is required once we have a new regulator. 3. I started an excel file to track all of our trials. I will upload it here sometime. (Comment on this)
Wednesday, October 4th, 2006
8:34 am	Update Again I've skipped a few days now, so time to update. Monday: This is a busy day classwise, so I really only looked around in the transformer for anything unusual. I was looking for some carbon contact that doesn't seem to exist. I did, however, find a spot on one of the transformers where it was arcing at some point in time. I disassembled the gun and replaced the 14S o-ring, the powder port plug, and the connector that sizes the waterhose down to the cathode holder. No more swivel connector- just a straight connector. I also got a package from Thermach today with the powder hoses, connector and Y-powder hose connector. I also received the latest copy of our budget, which I will balance when I am in Dodge City. Tuesday: Today I played around with the secondary that was arcing, and I tested resistances across several parts of a working secondary to see what was different. I couldn't find anything. I put it all back together and turned on everything at around 5:00. The plume was stable to 1000A, no problems. I also cleaned the hopper I was using for alumina/yttria, and started drying nickel powder, so I couldn't spray tonight even though everything appears to be working. I also vacuumed the booth and around the hoppers with the HEPA vacuum and attached the new powder hose Y and real powder hoses instead of the tygon tubing. Wednesday: Scott and I did two nickel spray runs this morning. Run 1: Arc Gas: Argon 50SLPM Aux Gas: Helium 0SLPM Powder Gas: Argon 6SLPM Current: 750A Voltage: 37.5V Standoff: 100mm Cooling: 30psi Air Wheel Speed: 1.5 RPM X/Y: 150mm/s and 150mm/s Step: 4 Passes: 1 Preheat, 5 regular Time Start: 8:19:40 Time Powder: 8:21:10 Time End: 8:23:00 Notes: Powder gas not on til after 1 regular pass Run 2: Arc Gas: Argon 50SLPM Aux Gas: Helium 10SLPM Powder Gas: Argon 7SLPM Current: 750A Voltage: 40.3V Standoff: 100mm Cooling: 30psi Air Wheel Speed: 1.5 RPM X/Y: 150mm/s and 150mm/s Step: 4 Passes: 1 Preheat, 5 regular Time Start: 8:29:08 Time Powder: 8:30:44 Time End: 8:32:16 Notes: n/a The voltage, current and plume were very stable in both runs. There was slight copper spraying at the initial strike, but nothing sustained. No powder was deposited, some powder feed issue. Upon reflection, it was decided that using the Y piece with the second hopper apart (and thus not pressurized) was probably the cause of this. (Comment on this)
Friday, September 29th, 2006
7:15 am	The last two days I have not posted anything for the last two days. Here is an update: Wednesday I have a full load of classes on Wednesday, so I did essentially nothing. I talked to Nathan about the problems and gave him an update on where we were in fixing things. I tested all capacitors and diodes on Tuesday, and all fell into a normal range. Thursday Work day: 8:30-11:30, 1:30-4:30 1. I rebuilt the transformer. I cleaned all contacts, nuts, bolts, washers and diodes with acetone and then methanol and only handled them with gloves in hopes of keeping the contact surfaces clean and of low resistance. I applied some silicone thermal grease to the aluminum plates to aid in heat dissipation. This process took forever, but the tricks I learned are to take off the grate in front of the capacitors and to work from right to left. If you try to work from left to right, it becomes hard to get the diodes in place. Once all parts are physically installed, then tighten everything down. 2. Scott and I powered up the system. Now, we are unstable below 400A (which is usual), but relatively stable between 400A-700A. Once you break 700A, the current suddenly jumps to over 1000A, which trips the automatic current limitation, and drops back down to say 650A. We did this twice. 3. There is also now a small internal water leak, as evidenced by dripping from the gun. We couldn't get it to drip unless the plasma was turned on. Another possibility is that the water leak was there when we tested for water leaks and for some reason there was water where I could not see it. When we turned on the plume, it blasted all that water out of the system. Not sure if this is likely or not, as I did not see any water on Tuesday. 4. I sent David and Ray and email updating them on the latest findings with the transformer. I also emailed Kendall about the dilatometer and the power supply. Today's goals: 1. Completely rebuild gun 2. Clean both hoppers 3. Try again! (Comment on this)
Tuesday, September 26th, 2006
3:40 pm	Diode Testing Today was mostly aimed at getting the power supply up and running. Today's work day: 6:30-1:00, 2:30-5:00 1. I ordered a Y-powder connector, 12' powder hose, and a new negative terminal adaptor for the SG-100. The adaptor is different than the current swivel type, but upon talking to people at Thermach, they said that the swivel type went away in the 90's, and was replaced with a straight connector. The only purpose of the connector is to adapt from a 7/8" water cooled power line to a 3/4" cathode holder. Total order: $218+shipping 2. I built a small test circuit which consisted of a 9V battery, 6V lamp, and alligator clips for testing the diodes. The test circuit lights when current flows, but does not light when current does not flow. It's a simple pass/fail test. I got the supplies from Norton for under $5. 3. Mike Ruth and I disassembled the transformer, removing all diodes, bolts, nuts, and washers. Before reassembling them, we will clean each contacting part with acetone, then methanol, then applying thermal grease. Mike picked up thermal grease for around $9 from Norton. 4. We tested all 24 diodes. All 24 showed current passing under one configuration, but not flowing under the opposite. This would hint that all 24 diodes are good. I will do a quantitative test of resistance later. 5. I received a few emails from Dr. H as well as Ray. One suggestion says to see if our rectifier is properly grounded (12-15' copper rod). I cannot find this. It is possible that it is buried under a rail, as the transformer sits on two of them. Ray wants to know what is actually the problem and what are we seeing on this end. 6. I brought in my multimeter to measure capcaitatnce on all filtering capacitors. I can also measure the resistance both directions. 7. DTA run seems to have worked right. Scott knows more, I'll have to chat with him about it. Stuff for Tomorrow: 1. Measure capacitances 2. Measure resistances 3. Start reassembly of transformer (Comment on this)
Monday, September 25th, 2006
10:57 pm	Welcome Welcome to my livejournal. I will put my work related stuff here as a back-up to my lab book. Today's work day: 9:00-12:30, 2:00-5:30 1. I swapped an email with Daryl Crawmer. He recommended a few people to contact about our power supply problems, and also advised me to check the SG-100 for water leaks. He also provided me with Ray Selby's contact info. 2. I called Ray Selby and he said he was convinced that our problem was the power diodes in the Plasmadyne PS-61 transformer. He told me he would check with a few people as well. 3. Ray called back and told me that was the biggest suspect amongst his contacts as well. He told me to test them by taking out each diode and checking the resistance in one direction and then in the other. 4. We started a DTA run. I had to find the reference weight for the alumina which was 176.87mg. 5. I tested for a water leak in the gun by switching on only the water (no high voltage, no gases) and hoping to "flood" the gun. I left it on for five minutes, until someone used enough water to trip the water safety in the control box. I turned it back on for another 25 minutes around lunch time. There was no internal leaks, though a slight external one, coming from the where the negative cable attaches to the back of the gun. I should order a part from thermach to replace this. 6. I took apart the Plasmadyne PS-61. To get to the diodes, I had to remove the top of the box, open both front doors, overload switch, power indicator, some giant varistor, remove the front panel, undo both the major positive and negative leads, the power control wires from the control box (white=positive, black=negative), and the black panel under the safety door. I removed one power diode and tested it both directions with my multimeter. One direction showed 1.7Mohms, and the other showed 2.5Mohms. This could be suspect, or it could be normal, I am not sure. 7. Went in search of a parts sheet for my power diode, but to no luck. Atta helped with that. 8. I talked to my dad about measuring the diode resistance and he said that Ray's suggestion was a good method, though he is not sure whether my multimeter is putting out enough of a bias voltage to actually open the diode. My dad also agreed with my suggestion of building a test ciruit which guarantees proper bias voltage across the diode. He says to make sure to put a series resistance (a lightbulb would work) to make sure that there is not too much current flowing through the diode, though it probably won't hurt my diodes. Hopefully tomorrow: 1. Start another DTA run 2. Order negative terminal extension 3. Maybe build a test circuit for testing diodes (Comment on this)