U.S. patent application number 11/159402 was filed with the patent office on 2006-02-09 for tib2 rod, and method of fabrication and use.
This patent application is currently assigned to Huy's Industries Limited. Invention is credited to Shijie Dong, Norman Zhou.
Application Number | 20060029512 11/159402 |
Document ID | / |
Family ID | 34603544 |
Filed Date | 2006-02-09 |
United States Patent
Application |
20060029512 |
Kind Code |
A1 |
Dong; Shijie ; et
al. |
February 9, 2006 |
TiB2 rod, and method of fabrication and use
Abstract
A TiB.sub.2 rod, and a method of fabrication therefore are is
provided. It may be used to producing a TiB.sub.2 coating on the
tip surfaces of a resistance spot welding (RSW) electrode, such as
may be of a type for welding applications in automotive, and
electronic industries. There may be a rod of material for coating
the tips of welding rods that includes TiB.sub.2 ceramic having
good electrical and thermal conductivities and a high melting
temperature. The new TiB.sub.2 rod may be used to produce a
TiB.sub.2 coating on an electrode tip surfaces by ESD, which may
tend to be low in cost and which may tend to produce a higher
electrode life as compared to an embodiment of TiC coating.
Inventors: |
Dong; Shijie; (Shiyan,
CN) ; Zhou; Norman; (Waterloo, CA) |
Correspondence
Address: |
Ralph A. Dowell of DOWELL & DOWELL P.C.
2111 Eisenhower Ave
Suite 406
Alexandria
VA
22314
US
|
Assignee: |
Huy's Industries Limited
|
Family ID: |
34603544 |
Appl. No.: |
11/159402 |
Filed: |
June 23, 2005 |
Current U.S.
Class: |
419/38 ;
75/245 |
Current CPC
Class: |
B22F 2998/10 20130101;
B22F 2998/10 20130101; B23K 35/327 20130101; B23K 35/402 20130101;
B22F 3/1021 20130101; B22F 1/0003 20130101; B22F 9/04 20130101;
C22C 29/14 20130101; B22F 3/14 20130101 |
Class at
Publication: |
419/038 ;
075/245 |
International
Class: |
B22F 1/02 20060101
B22F001/02; C22C 5/00 20060101 C22C005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 8, 2004 |
CN |
200410060704.4 |
Claims
1. A TiB.sub.2 rod to for use in coating an RSW electrode tip
surfaces using EPD, said rod including (in weight percentage):
12-24 Ni, 4-10 Mo, 0.15-1.0 W, 0.15-1.0 Co, and balance
TiB.sub.2.
2. The rod of claim 1, including (in weight percentage): 15-20 Ni,
4-8.5 Mo, 0.5-L1.0 W, 0.3-1.0 Co, and balance TiB.sub.2 in claim
1.
3. A method of fabricating the rod of claim 1, said method
including the steps of obtaining powders of said Ni, Mo, W, Co and
TiB.sub.2; mixing said powders evenly; milling said powders for
24-96 hours; adding 2-10% binder; debinding 100-300.degree. C.; and
sintering under 10 MPa to 30 MPa pressure in controlled atmosphere
at 1500-1900.degree. C.
4. A method of fabricating the rod of claim 2 wherein said method
includes the steps of obtaining powders of said Ni, Mo, W, Co and
TiB.sub.2; mixing said powders evenly; milling said powders for
48-72 hours; adding 2-10% binder; debinding 100-300.degree. C.; and
sintering under 10 MPa to 30 MPa pressure in controlled atmosphere
at 1650-1800.degree. C.
Description
AREA OF APPLICATION OF INVENTION
[0001] The TiB.sub.2 coating rod, such as may be used to provide by
an electrospark deposition (ESD) coating layer on a welding
electrode may be used in the field of Resistance Spot Welding (RSW)
such as may be used, for example, in applications in industries
such as the Automotive and Electronics industries.
TECHNICAL BACKGROUND
[0002] With the progress in the automotive industry, regular sheet
steels can not meet the corrosion-resistant requirement. Various
coated sheet steels, such as Zinc coated steels for example, may be
found in an increasing number of applications in automobiles.
However, the resistance spot welding of zinc coated steels may
necessitate a higher welding current or longer weld time as
compared to uncoated bare steel, because of the lower melting point
of Zn and hence the reduced contact resistance as compared to bare
steels. This may tend to increase the operating temperature of the
electrodes. Under the combined effects of heat and pressure, the
electrodes may tend to react with the Zn coating to form low
melting point alloys. The formation of these alloys may tend to
hasten degradation of the electrodes. Therefore, researchers have
tried to find methods to improve electrode base materials, and to
modify the electrode surface conditions. The surface modification
methods may be more effective and may be less expensive. A coating
layer, which may be a ceramic coating layer, such as may be
deposited on electrode surfaces may have a high melting point, high
electrical conductivity, high strength and low reactivity with Zn.
Such a coating may tend to stop or minimize the reaction between
the electrodes and the Zn coating, and hence may tend to improve
electrode tip life, and may tend to reduce the sticking tendency
between the electrode and the workpiece. As such, there is a need
for an advantageous coating material for application on the
electrode tip surfaces.
[0003] The major surface modification methods include PVD (physical
vapor deposition) and ESD (Electrospark Deposition). Others have
made observations in this field. For example, Gobez [1] applied Co,
Ta, Ni, TiN or Mo on CrZrCu electrode, and the results indicated
that the first three coatings decreased the electrode tip life but
the last two improved the wear resistance of the electrode. Studdon
[2] at Wollongong University used TiN on Zn--Al coated steels, and
the results indicated 70% improvement in electrode tip life.
Ashcroft et al. [3] applied CrN using PVD on Zn--Al coated steels,
the results indicated that the welding current was reduced by 10%
but no improvement in electrode life was experienced. But the
electrode life was stable at .+-.7% compared to .+-.40% with
electrode coating. TiC coating was used to improve electrode tip
life in microwelding and the results showed the TiC coating by EDS
improve the tip life by 200% (from 600 to 1200) because the TiC
coating reduced the local bonding between electrodes and Ni-coated
steel and the deformation of the electrodes. The TiC coating by
Huys Industries can also improve the electrode sticking resistance.
It improved the CuCrZr electrode life in RSW of Zn-coated steels
for automotive applications by 250% (from 400 for the uncoated
electrodes to 1000 for coated electrodes).
DETAILED DESCRIPTION
[0004] By way of general overview, this description pertains to a
TiB.sub.2 rod and its fabrication for the use of producing
TiB.sub.2 coating on resistance spot welding (RSW) electrode tip
surfaces for welding applications in automotive, and electronic
industries. There may be a rod of material for coating the tips of
welding rods that includes TiB.sub.2 ceramic having good electrical
and thermal conductivities and a high melting temperature. The new
TiB.sub.2 rod may be used to produce a TiB.sub.2 coating on an
electrode tip surfaces by ESD, which may tend to be low in cost and
which may tend to produce a higher electrode life as compared to an
embodiment of TiC coating.
[0005] In one embodiment, there may be a TiB.sub.2 coating rod for
the use of coating on RSW electrode tip surface by ESD. That rod
may have a chemical composition of, in wt %, 12-24 Ni, 4-10 Mo,
0.15-1.0 W, 0.15-1.0 Co, and balance TiB.sub.2. This rod may be
used for electrospark deposition (ESD) on RSW electrode tip
surfaces in automotive and electronics industries.
[0006] An aspect of this invention also covers the fabrication of
the TiB.sub.2 rod for the use of producing TiB.sub.2 coating on RSW
electrode tip surfaces. The rod may be fabricated as follows:
[0007] 1. Powders of Ni, Mo, W, Co and TiB at the above mentioned
weight percentage are mixed uniformly and milled for 24-96 hours.
[0008] 2. Binder is then added and the mixture is formed into a
green rod. [0009] 3. The rod is debinded and sintered under 10 MPa
to 30 MPa pressure in a controlled atmosphere at 1500-1900.degree.
C.
[0010] Debinding may refer to heating or baking the green rod for a
period of time at moderate, non-sintering temperatures prior to
sintering.
[0011] This TiB.sub.2 rod may be used to coat a layer using ESD
onto the RSW electrode tip surface. The coated layer may typically
be of the order of 10-25 .mu.m in thickness, and may tend to be
very stable. The coated layer may tend to improve the tip life of
conventional electrodes (such as Cu--Cr--Zr), without tip dressing.
In one embodiment the improvement may be about by 280%, or as much
as 1400 cycles, without tip dressing. The TiB.sub.2 layer may tend
to improve tip life, and may tend to be relatively inexpensive.
[0012] In a preferred embodiment, the rod may have a rod
composition (in weight percentage) of: 15-20 Ni, 4-8.5 Mo, 0.5-1.0
W, 0.3-1.0 Co, and balance TiB.sub.2. It may be milled for 48-72
hours. It may be sintered in a temperature range of
1650-1800.degree. C.
[0013] A few experimental examples will be given to illustrate,
using tables, the performance of the TiB.sub.2 coating on electrode
tip surfaces using embodiments of TiB.sub.2 rods, as a comparison
to TiC coating.
[0014] Table 1 shows the chemical compositions (all in weight
percentages) of four samples of different TiB.sub.2 rods as
compared to the TiC rod. It also indicates the average times needed
to coat a domed electrode of 16 mm in diameter and 8 mm in radius.
It is shown that all four samples of the TiB.sub.2 rods are similar
to TiC rods and may be used as coating rods for the ESD coating of
RSW electrode surfaces.
[0015] Table 2 shows a comparison of the tip life of the coated
electrodes with the four TiB.sub.2 and TiC rods in RSW of 0.8 mm
thick Zn-coated steel. It indicates that the electrode life using
the TiB.sub.2 coating by the four TiB.sub.2 rods is improved as
compared to the TiC coated electrode. The following are the details
of the examples: [0016] Sample No. 1 Mixing uniformly of powders of
736 g TiB.sub.2, 185 g Ni, 61 g Mo, 9 g W, and 9 g Co and then
milling the mixture for 52 hours. The mixed powders are made into
green rods by adding 83 g binder and then debinded at 220.degree.
C., and then sintered under 10 MPa pressure in a controlled
atmosphere at 1710.degree. C. [0017] Sample No. 2 Mixing uniformly
of powders of 756 g TiB.sub.2, 184 g Ni, 42 g Mo, 10 g W, and 8 g
Co and then milling the mixture for 60 hours. The mixed powders are
made into green rods by adding 75 g binder and then debinded at
270.degree. C., and then sintered under 10 MPa pressure in a
controlled atmosphere at 1780.degree. C. [0018] Sample No. 3 Mixing
uniformly of powders of 748 g TiB.sub.2, 156 g Ni, 85 g Mo, 6 g W,
and 5 g Co and then milling the mixture for 52 hours. The mixed
powders are made into green rods by adding 91 g binder and then
debinded at 190.degree. C., and then sintered under 10 MPa pressure
in a controlled atmosphere at 1680.degree. C.
[0019] Sample No. 4 Mixing uniformly of powders of 757 g TiB.sub.2,
162 g Ni, 71 g Mo, 7 g W, and 3 g Co and then milling the mixture
for 52 hours. The mixed powders are made into green rods by adding
86 g binder and then debinded at 280.degree. C., and then sintered
under 10 MPa pressure in a controlled atmosphere at 1750.degree. C.
TABLE-US-00001 TABLE 1 Composition of the rods and coating time
Example TiC for 1 2 3 4 comparison TiB2 73.6 75.6 74.8 75.7 Ni 18.5
18.4 15.6 16.2 Mo 6.1 4.2 8.5 7.1 W 0.9 1.0 0.6 0.7 Co 0.9 0.8 0.5
0.3 Coating time 57 59 61 56 65 (Seconds)
[0020] TABLE-US-00002 TABLE 2 Average electrode tip life 0.8 mm
thick Zn-coated steel TiC 1000 Example 1 1400 Example 2 1500
Example 3 1550 Example 4 1450
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