U.S. patent application number 10/219026 was filed with the patent office on 2003-06-05 for compositions of manganese sulfide compound added for making sintered product.
Invention is credited to Kim, Hyung Bum, Park, Dong Kyu.
Application Number | 20030101849 10/219026 |
Document ID | / |
Family ID | 19716493 |
Filed Date | 2003-06-05 |
United States Patent
Application |
20030101849 |
Kind Code |
A1 |
Park, Dong Kyu ; et
al. |
June 5, 2003 |
Compositions of manganese sulfide compound added for making
sintered product
Abstract
Compositions of a manganese sulfide (MnS) compound useful as
additives for making a sintered product are disclosed, in which
molybdenum (Mo) or Fe--Mo is added to the MnS compound to improve
machinability and to obtain a more stable MnS compound, thereby
reducing any change in weight and size in a sintering process. The
compositions can suppress erosion of parts in a sintering furnace
during a sintering process, prevent sooting on a surface of the
sintered product from occurring, and enhance resistance to moisture
in the air to keep the sintered product in the air for a long
time.
Inventors: |
Park, Dong Kyu;
(Pusan-kwangyokshi, KR) ; Kim, Hyung Bum;
(Yangsan-shi, KR) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN
6300 SEARS TOWER
233 SOUTH WACKER
CHICAGO
IL
60606-6357
US
|
Family ID: |
19716493 |
Appl. No.: |
10/219026 |
Filed: |
August 14, 2002 |
Current U.S.
Class: |
75/230 |
Current CPC
Class: |
C22C 33/0221 20130101;
B22F 1/0003 20130101; C22C 29/00 20130101 |
Class at
Publication: |
75/230 |
International
Class: |
C22C 029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2001 |
KR |
P2001-75389 |
Claims
What is claimed is:
1. A composition of manganese sulfide (MnS) useful as an additive
for making a sintered product comprising MnS and added molybdenum
(Mo) or Fe--Mo in an amount effective to improve machinability.
2. The composition of claim 1, comprising about 0.5 wt % to about
10 wt % added Mo.
3. The composition of claim 1, comprising about 4 wt % to about 8
wt % added Fe and about 0.5 wt % to about 15 wt % added Mo.
4. The composition of claim 3, comprising about 1.0 wt % to about
6.0 wt % added Mo.
Description
BACKGROUND OF THE DISCLOSURE
[0001] 1. Field of the Disclosure
[0002] The disclosure relates to compositions of manganese sulfide
(MnS) compounds useful as additives for making a sintered product
to enhance machinability and, more particularly, to compositions of
a MnS compound useful as additives for making a sintered product
that can be preserved for a long time by enhancing resistance to
moisture in the air.
[0003] 2. Discussion of the Related Art
[0004] Generally, manganese sulfide (MnS) is a kind of a metal
sulfide and is used as an additive to raw materials to enhance
machinability in making a sintered product. The MnS may be used as
a solid lubricant.
[0005] Currently manufactured MnS is a pure form of MnS, which is
manufactured so that sulfur (S) rather than manganese (Mn) is in
excess. Surplus sulfur reacts with oxygen, zinc, and the like under
the atmosphere of a sintering furnace during the sintering process,
resulting in problems. For example, excess sulfur erodes mesh belts
of heat-resistant steel, muffle, or fireproof material, which is
formed in the furnace, and may remain on a surface of the product
to cause sooting.
[0006] To solve such problems, to make up for heat loss in the
manufacturing process, and to improve productivity, a manganese
sulfide compound and its method of production have been disclosed
in U.S. Pat. No. 5,768,678. In this patent, a MnS compound of
Fe--Mn is manufactured. In this case, since a considerable amount
of sulfur remains in excess, the problems described herein still
occur in the sintering process.
[0007] Recently, attempts to manufacture a metal sulfide by mixing
sulfur with metal using a mechanical-chemical method have been made
in Korean Patent Applications Nos. 1999-0026303, 2001-0007298, and
2001-0007299. In case of MnS manufactured by this method, excess
sulfur has been considerably reduced. However, a problem still
remains in the sintering process. Also, since such MnS has
hygroscopic that absorbs moisture in the air, problems occur in
preservation and use after manufacturing it.
SUMMARY OF THE DISCLOSURE
[0008] Accordingly, the disclosure is directed to compositions of a
MnS compound useful as additives for making a sintered product that
substantially obviate one or more problems due to limitations and
disadvantages of the related art.
[0009] The disclosure provides compositions of MnS useful as
additives for sintered products in which molybdenum (Mo) or Fe--Mo
is added to MnS to obtain a MnS compound that is more stable than
pure MnS, thereby reducing changes in weight and size in a
sintering process.
[0010] The disclosure also provides compositions of MnS useful as
additives for making sintered products that suppress erosion of
parts in a sintering furnace during a sintering process, preventing
sooting on a surface of the sintered product from occurring, and
enhancing resistance to moisture in the air to keep MnS in the air
for a long time.
[0011] Additional advantages, objectives, and features of the
disclosure are set forth in part in the description which follows
and may become apparent to those having ordinary skill in the art
upon examination of the following or may be learned from practice
of the disclosure. The objectives and other advantages of the
disclosure may be realized and attained by the structure
particularly pointed out in the written description and claims
hereof as well as the appended drawings.
[0012] To achieve these objectives and other advantages and in
accordance with the purpose of the disclosure, as embodied and
broadly described herein, compositions of a manganese sulfide (MnS)
compound useful as additives for making a sintered product are
characterized in that molybdenum (Mo) or Fe--Mo is added to the MnS
compound to improve machinability.
[0013] Both the foregoing general description and the following
detailed description are exemplary and explanatory.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings are included to provide a further
understanding of the disclosure and illustrate embodiments of the
disclosure. In the drawings:
[0015] FIG. 1 illustrates a device for mixing a MnS compound;
[0016] FIG. 2 illustrates peaks of a phase analysis;
[0017] FIG. 3 is a graph illustrating changes of a decrease rate in
weight after passing through a sintering furnace when Mo is added
to a MnS compound;
[0018] FIG. 4 illustrates a device for testing hygroscopicity;
[0019] FIG. 5 is a graph illustrating change in hygroscopic amount
after the elapse of time;
[0020] FIG. 6 is a graph illustrating a change rate in weight when
a MnS compound powder of 0.5% is added to a sintered steel;
[0021] FIG. 7 is a graph illustrating a dimensional change when a
MnS compound powder of 0.5% is added to a sintered steel; and
[0022] FIG. 8 is a graph illustrating a change rate in weight after
passing through a sintering furnace when Mo and Fe are
simultaneously added to a MnS compound.
DETAILED DESCRIPTION
[0023] Reference will now be made in detail to preferred
embodiments of the disclosure, examples of which are illustrated in
the accompanying drawings. Wherever possible, the same reference
numbers will be used throughout the drawings to refer to the same
or like parts.
[0024] Mo is independently added to a MnS compound in the range of
about 0.5 wt % to about 10 wt % (the other 99.5 wt % to about 90 wt
% is MnS). If Mo is added to the MnS compound, a decrease rate in
weight during sintering is smaller than if Fe is added to the MnS
compound. This is because Mo forms MoS.sub.2 so that Mo interacts
with excess sulfur and the stability of Mn is greatly improved.
[0025] If a Mo--Fe compound is added to the MnS compound, Fe is in
the range of about 4 wt % to about 8 wt % of the composition and Mo
in the range of about 0.5 wt % to about 15 wt %, preferably, about
1.0 wt % to about 6.0 wt %, of the composition. In this case,
stability of the MnS compound can be improved. If the Mo
concentration is less than 0.5 wt %, the MnS compound is more
stable than pure MnS, but a relatively great decrease rate in
weight is generated. If Mo is in the range of about 6 wt % to about
15 wt %, the MnS compound has relatively excellent characteristics
but it is not economical due to the expense of Mo.
[0026] Therefore, the preferred MnS compound is obtained by adding
Mo of about 0.5 wt % to about 15 wt % to Fe of about 4 wt % to
about 8 wt %. More preferably, Mo contained in the composition is
in the range of about 1.0 wt % to about 6.0 wt %.
EXAMPLE 1
[0027] Mo--Fe powders of 0 wt %, 2.0 wt %, 4.0 wt %, 6.0 wt %, 8.0
wt %, 10.0 wt %, and 15. wt % were respectively added to a MnS
powder, and 3.0 kg were weighed to obtain a composition ratio of
1:1 between Mo--Fe powder and sulfur. As shown in FIG. 1, MnS 6
containing Mo and steel balls 3 (20 kg) were put in a rigid
container 1 of 15 liters volume. The rigid container 1 was provided
with a rotary shaft 2 and a motor 5 rotated at 600 rpm for thirty
minutes while heating the surface of the rigid container 1 and
temporarily heating the same up to 400.degree. C. by a heater 4 or
cooling the same to adjust heat energy. As a result, the MnS
compound was manufactured and is used in the following
experiments.
[0028] Phase Analysis and Component Analysis
[0029] X-ray diffraction (XRD) analysis and X-ray fluorescent (XRF)
analysis were carried out for phase analysis and component analysis
of the MnS compound. As a result, all peaks of the XRD were
observed as MnS phases. No difference between the related art MnS
and an improved MnS compound of the disclosure was observed. To
check whether an additive remained, a component of the MnS compound
was analyzed by XRF analysis. The analyzed result of the component
of the MnS powder showed the presence of Fe and Mo (see Table 1).
Therefore, Fe and Mo added to the improved MnS compound did not
affect the crystalline structure of the sulfide.
[0030] Test of Color Change
[0031] To test stability, 100 g of each of an improved MnS compound
and a pure MnS were respectively weighed in a ceramic crucible and
maintained in a sintering furnace under a reducing atmosphere at
1120.degree. C. for one hour. Mo of about 2 wt % to about 10 wt %
and Fe of about 4 wt % to about 8 wt % were added to the improved
MnS compound. Decrease in weight of the powder and color change in
the crucible were tested. The result of the test indicated that a
pollution level (color change) in the crucible containing the
improved MnS compound was reduced as compared with the related art
pure MnS compound. This means that a more stable MnS can be
manufactured by adding Mo and Fe having the above compositions to
the existing pure MnS. On the other hand, if Mo of 8 wt % or
greater and Fe of 6 wt % or greater are added to the MnS powder,
the pollution level increases and a decrease rate in weight of the
MnS powder increases. This is because that the stable MnS arises
from Mo and Fe. Accordingly, it is preferable that Mo of about 1.0
wt % to about 6.0 wt % is used.
[0032] Also, if Mo instead of Fe is added to the MnS compound, the
decrease rate in weight becomes smaller. This is because that Mo
forms MoS.sub.2 to interact with excess sulfur to improve stability
of Mn.
[0033] Test of the Hygroscopicity
[0034] To test the hygroscopicity in the air, as shown in FIG. 4, a
thermometer 8 and a timer 9 were set up at the upper part of a tank
7, and a container 10 with water and a glass saucer 12 for MnS 11
were disposed at the lower part of the tank 7. A device with a
temperature controller 13 was additionally provided at the bottom
of the tank. FIG. 5 shows the test result of the hygroscopicity by
measuring the respective increased amounts of the weight of 100 g
of MnS and MnS+Fe of the related art and MnS+Mo of the disclosure
on the glass saucer 12 after the lapse of time. The pure MnS and
MnS+Fe, as shown in FIG. 5, came to have more hygroscopicity, after
the lapse of time, compared to the improved MnS compound (MnS+Mo).
Moreover, after the lapse of time, not only the above difference
between the related art and the compound components increased, but
the color of a mass of a sulfide changed to dark red.
[0035] Test of Stability
[0036] To test stability in the practical product, MnS of 0.5 wt %
according to the prior art and according to the disclosure were
added to a sintered steel having compositions of
Fe-4Ni-0.4Mo-1.5Cu-0.8C. The resultant product was compacted and
sintered at the same density of 6.8 g/cm.sup.3 to measure the rate
of weight loss and any dimensional change.
[0037] As a result, as shown in FIGS. 6 and 7, a smaller decrease
in weight loss and a more stable size were indicated in the MnS
compound of the disclosure. Since the MnS compound of the
disclosure had a small change in size after addition of MnS, an
originally manufactured molding was used until the final product is
completed. This is very important in the field of powder metallurgy
of which size of the final product is determined by molding.
EXAMPLE 2
[0038] While Mo and Fe of transition metals were respectively added
and tested in the Example 1, in Example 2 Mo and Fe were
simultaneously added to manufacture a stable metallic compound. Fe
was added at a greater amount than an amount of the relatively
expensive Mo.
[0039] The content of Fe was fixed at 6% corresponding to the range
having the most excellent characteristic in Example 1. Mo was added
by each of 2 wt %, 4 wt %, 6 wt %, 8 wt %, and 10 wt % so that the
MnS compound was manufactured by the same process as that of
Example 1. Then, the remainder of the MnS compound after passing
through the sintering furnace at the powder state was tested by the
same method as that of Example 1. The result of the test is shown
in FIG. 8.
[0040] As will be apparent of it from FIG. 8, the stability of MnS
was remarkably improved even if Fe and Mo were simultaneously added
to the MnS compound. If Mo is added to the MnS compound at a small
content (0.5 wt % or less), a relatively great decrease rate in
weight was indicated, even if the MnS compound of the Example 2 is
more stable than the pure MnS. However, in this case, a problem
arose in that the practical advantages were reduced. If Mo of about
6 wt % to about 15 wt % is added to the MnS compound, excellent
characteristics can be obtained but it is not economical due to its
expense. Therefore, the preferred composition of the MnS compound
includes Fe of about 4 wt % to about 8 wt % and Mo of about 0.5 wt
% to about 15 wt %. More preferably, the MnS compound includes Fe
of about 4 wt % to about 8 wt % and Mo of about 1.0 wt % to about
6.0 wt %.
1 TABLE I MnS Fe-MnS Mo-MnS Mn 62.9 59.7 57.1 S 36.0 33.5 39.6 Fe
0.63 6.81 0.58 Cu Mo 6.2 O 0.32 0.3 0.27 C 0.15 0.14 0.18
[0041] The compositions of MnS compound according to the disclosure
have the following advantages.
[0042] Since the compositions of the MnS compound, such as Fe and
Mo, are useful additives for making a sintered product, stability
of the product can be enhanced and a decreased rate of weight loss
is demonstrated. Also, since adverse effects to the product are
reduced, the life span of the sintering furnace increases and
discoloration of the product are reduced. Resistance to oxidation
increases due to low hygroscopicity. This reduces problems related
to packing and storage of the product. Enhanced dimensional
stability can enable the product to be manufactured without newly
making a mold and can enhance accuracy of the manufacturing
process.
* * * * *