Title of Invention

A PROCESS OF MAKING VITREOUS COATING COMPOSITION SUITABLE FOR YELLOW VARIETY BRASS SUBSTRATE.

Abstract The present invention relates to a process of making vitreous coating composition suitable for yellow variety brass substrate. The coatings made out of this glass composition may be used as a scratch and impact resistant decorative items against environmental abatements like weathering effects in the areas of appliances like decorative items in doors, windows and costly metal vessels made of yellow variety brass. The invention relates to the formulation of a glass composition for coating the surfaces of brass of yellow variety composed of alkaline-lead-boro-silicate glassy phase. The glass composition can be applied on yellow variety brass substrate by simple and cost effective vitreous enamelling process.
Full Text The present invention relates to a process of making vitreous coating composition
suitable for yellow variety brass substrate.
This invention particularly relates to a process of making the formulation of a glass composition for coating the surfaces of brass of yellow variety composed of alkaline-lead-boro-silicate glassy phase. The glass composition can be applied on yellow variety brass substrate by simple and cost effective vitreous enamelling process as described hereinafter. The glassy coating provides environmental protection as well as scratch and impact resistance property to the metallic components viz. yellow variety brass to enhance the service life and aesthetic values as well as decorative items in doors, windows and costly metal vessels made of yellow variety brass. Vitreous enamel coatings or glass coatings on brass as well as copper are known to provide limited protection to this kind of metallic substrates, as reported in the articles, (1) "Art Enamelling on Metal", J. Minneman, Trans. Am. Ceram. Soc. 13 (1912) 514, only a treatise on art enamelling. (2) "The Production of Some White Enamels for Copper", R. R. Danielson and H. P. Reinecker, J. Am. Ceram. Soc. 4 (1921) 827-834, which deals with the development of some white enamels for copper substrate along with the effect of varying Na2O, PbO, Cryolite, SiO2 and B2O3 on the properties of the enamels. (3) "Auger Analysis of Brass-Enamel and Stainless Steel Enamel Interfaces", D. E. Clark, C. G. Pantano, Jr. and G. Y. Onoda, Jr., J. Am. Ceram. Soc. 58 [7-8](1975)316-322, wherein dry fritted 80 mesh enamel (borosilicate) was sprinkled on to the specimens and isothermally fired at 843°C for 1 min to yield a smooth and homogeneous coating ~ 10 mils thick. (4) "Art Enamels for Copper", E. A. Yatsenko, A. M. Kondyurin, V. P. Ratkova and N. N. Tkachenko, Glass Ceram. 54[3-4](1997)93-95, wherein a single low melting glass matrix in the system R2O-PbO-B2O3-SiO2 (R = Na, K) on copper was applied by maturing at 680°-700°C. Drawbacks of the above processes are as follows:
(1) Although the thermal co-efficient of linear expansion of jewellery enamels are close
to that of brass, since brass contains zinc in addition to copper, the sole enamel
which was suitable for copper enamelling, are not suitable for enamelling of brass
which contains zinc.
(2) The copper substrate are required to give a very light wash of the enamels ground in
water to prevent excessive oxidation of metal during the firing process.
(3) The slow radiation of heat from the muffle walls and the highly oxidising conditions of
the furnace atmosphere tend to excessive oxidation of copper before the enamel is
fused.
(4) The substrate deformation up to 7% has also been reported.
(5) The manufacture of household pieces of art from non-ferrous metals decorated with
jewellers' enamels is a labour oriented and technologically complicated process.
Existing colour jewellers' enamels are expensive and melt in a wide temperature
interval (800°-950°C). Because of this, their use in a single piece of art is a
challenging technological task and the manufacturing cost is high.
After making literature and patent searches we have not been able to get, to the best of
our knowledge any coating composition suitable for yellow variety brass.
The main object of the present invention is to provide a process of making vitreous
coating composition suitable for yellow variety brass substrate.
Another object of the present invention is to provide an alkaline- lead- boro- silicate
glassy phase in the matured composition.
Still another object of the present invention is to provide the glassy coating composition
prepared in the form of a slip by wet milling process.
Yet another object of the present invention is to provide scratch and impact resistant
decorative coating against environmental abatements and to increase the service life of
the metallic components made of yellow variety brass.
Still another object of the present invention is to provide a process for preparation of
vitreous coating for yellow variety brass substrate which can be coated at a relatively
lower temperatures (800° to 850°C).
Yet another object of the present invention is to provide a coating composition which
allows shorter time period of firing (3 to 5 min) so that the metal base i.e. yellow variety
brass can be safely heated without any adverse effect on the metal surface.
Still another object of the present invention is to provide a good adherent glassy coating
material made of the above referred vitreous composition on yellow variety brass
substrate which needs the composition of glassy phase must have a co-efficient of
linear thermal expansion matching to that of the metal
(yellow variety brass) to be coated so that the peeling or chipping of the glassy coating
do not occur from the brass substrate.
Yet another object of the present invention is to provide the adherence property
achieved by considering oxide factors of the composition of glassy phase and is so
formulated that their co-efficient of linear thermal expansion matches with that of the
metallic substrate viz. yellow variety brass.
Still another object of the present invention is to provide a process for making vitreous
coating composition for surfaces of metallic components made of yellow variety brass
which is economic, scratch and impact resistant against environmental abatements.
Accordingly, the present invention provides a process of making vitreous coating
composition suitable for yellow variety brass substrate which comprises mixing quartz
20.0 to 21.2 wt%, sodium nitrate 20.0 to 21.4 wt%, potassium carbonate 4.8 to 5.8 wt%,
calcium carbonate 3.6 to 4.3 wt%, anhydrous alumina 0.4 to 0.8 wt%, boric acid 9.2 to
10.2 wt%, arsenious oxide 2.8 to 3.5 wt% and litharge 32.8 to 39.2 wt% by known
processes, melting the said mixture at a temperature in the range of 1200 to 1250
degree C, pouring the melted mixture into water kept at room temperature to obtain a
fritted glass, mixing 62.04 to 68.66 wt% of the fritted glass so obtained with 1.24 to 2.17
wt% suspending agent, 0.03 to 0.06 wt% electrolyte, 2.40 to 4.34 wt%, maturing range
promoter, 0.17 to 0.31 wt% adhering agent, 0.03 to 0.06 wt% water soluble organic
polymer and 27.46 to 31.02 wt% iron free water by conventional method, milling the
mixture to -250 to -300 mesh size [B.S. sieve] to obtain the vitreous coating composition.
In an embodiment of the present invention the raw materials used for making glass frit
are of commercial grade. In an embodiment of the present invention the suspending agent used may be such as china clay, kaolin, bentonite of commercial grade.
In another embodiment of the present invention the electrolyte used may be such as
barium chloride, sodium chloride, potassium chloride of commercial grade.
In still another embodiment of the present invention the maturing range promoter used
may be such as quartz, colloidal silica, precipitated silica of commercial grade.
In yet another embodiment of the present invention the adhering agent used may be
such as cobalt oxide, nickel oxide, manganese dioxide of commercial grade.
In still another embodiment of the present invention the water soluble organic polymer
used may be such as sodium carboxymethyl cellulose, methyl cellulose, polyvinyl
alcohol of commercial grade.
The process steps of the present invention are:
1. A batch material (500g) is prepared by mixing the ingredients thoroughly as given in the following table,
(Table Removed)

2. The above mixture was melted at a temperature in the range of 1200°-1250°C.
3. The molten material was quenched by pouring the said liquid into water kept at room
temperature to obtained a frit.
4. The above stated 100 g of fritted glass was properly mixed with the following
materials as given in the following table :

(Table Removed)
5. Said mixture was milled to -250 to -300 mesh size ( B.S. sieve ) to get the vitreous coating material in the form of a slip.
The novelty of the present invention lies in preparing a novel coating composition suitable for yellow variety brass substrate, for which to the best of our knowledge there is no known vitreous coating on yellow variety brass substrate. The inventive steps is in preparing alkaline-lead-borosilicate glassy phase in the frit form which is suitable for making a coating slurry for application on a yellow variety brass substrate. The vitreous coating composition of the present invention is suitable for application on yellow variety brass substrate which contains zinc in addition to copper and as a result known vitreous enamel coating can not be applied on yellow variety brass substrate. The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.
Example 1
A batch material (500 g) was prepared by mixing the following ingredients :
106 g quartz (SiO2)
50 g boric acid (H3BO3)
103 g sodium nitrate (NaNO3)
28 g potassium carbonate (K2CO3)
19 g calcium carbonate (CaCO3)
16 g arsenious oxide (As2O3)
3 g anhydrous alumina (AI2O3)
175 g litharge (yellow, PbO)
The above stated batch material was melted at 1200°C in oxidising atmosphere and subsequently the molten mass was quenched in iron free water to obtain glass flakes called "Frit". This frit (100 g) was milled along with other mill additives viz. , clay 2 g, cobalt oxide 0.3 g, barium chloride 0.06 g, water soluble organic polymer 0.06 g, quartz 4 g and iron free water 40 g, to obtain a slurry having particle size -250 mesh (B.S. sieve). The same slurry was used for coating the surfaces of yellow variety brass substrate.
Results of the properties obtained with the coated articles made from the invented coating composition is given in the table below:
(Table Removed)
Example 2
A batch material (499.5 g) was prepared by mixing the following ingredients :
105.5 g quartz (SiO2)
51.0 g boric acid (H3BO3)
107.0 g sodium nitrate (NaNO3)
29.0 g potassium carbonate (K2CO3)
21.5 g calcium carbonate (CaCO3)
17.5 g arsenious oxide (As2O3)
4.0 g anhydrous alumina (AI2O3)
164.0 g litharge (yellow, PbO)
The above stated batch material was melted at 1225°C in oxidising atmosphere and subsequently the molten mass was quenched in iron free water to obtain glass flakes called "Frit". This frit (100 g) was milled along with other mill additives viz. , clay 2.5 g, cobalt oxide 0.4 g, barium chloride 0.07 g, water soluble organic polymer 0.07 g, quartz 5 g and iron free water 45 g, to obtain a slurry having particle size -275 mesh (B.S. sieve). The same slurry was used for coating the surfaces of yellow variety brass substrate. Results of the properties obtained with the coated articles made from the invented
coating composition is given in the table below:
(Table Removed)
Example 3
A batch material (500 g) was prepared by mixing the following ingredients 100 g quartz (SiO2) 46 g boric acid (H3BO3) 100 g sodium nitrate (NaNO3) 24 g potassium carbonate (K2CO3) 18 g calcium carbonate (CaCO3) 14 g arsenious oxide (As2O3) 2 g anhydrous alumina (AI2O3) 196 g litharge (yellow, PbO)
The above stated batch material was melted at 1250°C in oxidising atmosphere and subsequently the molten mass was quenched in iron free water to obtain glass flakes called "Frit". This frit (100 g) was milled along with other mill additives viz. , clay 3 g, cobalt oxide 0.45 g, barium chloride 0.08 g, water soluble organic polymer 0.08 g, quartz 6 g and iron free water 50 g, to obtain a slurry having particle size -300 mesh (B.S. sieve). The same slurry was used for coating the surfaces of yellow variety brass substrate.
Results of the properties obtained with the coated articles made from the invented coating composition is given in the table below:
(Table Removed)
The main advantages of this invention are :
1. The thin vitreous coating composition as described earlier can be used for coating
yellow variety brass surfaces by conventional vitreous enamelling technique which is simple and cost effective as compared to hitherto known processes.
2. Repeated melting of the above said composition (glass frit) tends to promote opacity
and to eliminate dissolved gases.
3. Properties can be tailored by adjusting composition (glass frit) of the coated articles.
4. Controlled use of sodium oxide and arsenic maintain the desired property of opacity
without affecting gloss of coating material with least health hazard
5. Tendency to "over smelt" may be controlled by using sodium oxide and arsenic oxide.
6. Controlled use of sodium oxide and boric oxide combination reduce the tendency of
attacking copper.
7. The present vitreous coating system provides a good adherence on yellow variety
brass surfaces with fairly high thickness ( 80-100).




We claim:
1) A process of making vitreous coating composition suitable for yellow variety brass substrate which comprises mixing quartz 20.0 to 21.2 wt%, sodium nitrate 20.0 to 21.4 Wt%, potassium carbonate 4.8 to 5.8 wt%, calcium carbonate 3.6 to 4.3 wt%, anhydrous alumina 0.4 to 0.8 wt%, boric acid 9.2 to 10.2 wt%, arseniuos oxide 2.8 to 3.5 wt% and litharge 32.8 to 39.2 wt% by known processes to obtain batch rnatenal. melting the said batch material at a temperature in the range of 12000-12500C, pouring the meltedlmees into water kept at room temperature to obtain a fritted glass, mixing 62.04 to 68.66 wt% of the fritted glass so obtained with 1.24 to 2.17 wt% suspending agent, 0.03 to 0.06 wt% electrolyte, 2.40 to 4.34 wt% maturing range promoter, 0.17 to 0.31 wt% adhering agent , 0.03 to 0.06 wt% water soluble organic polymer and 27.46 to 31 .02 wt% iron free water by conventional method, milling the mixture to -250 to -300 mesh size (B.S. sieve) to obtain the vitreous coating material n the ~ form
A process as claimed in elaim I whereil9 raw mate.eiale use~i kr makina a lass frit are comm.ercial
A process as claimed in claims wherein the suspending agent used are
china clay, kaolin, bentonite ~f oomm&oa wad.
A process as claimed in claim4 1 ~4-wherein the electrolyte used are barium
chloride, sodium chloride, potassium chloride.
A process as claimed in claim~ I ,herein the maturing range promoter used are
au.ch as quartz, colloidal silica, precipitated silica,of comrn~~al grcdz.
A process as claimed in claims 1~ ,-~ wherein the adhering agent a~- used obalt oxide, ckel oxide, manganese dioxide,ef oemm~reiel'giede
A process as claimed in claims 1,~ e'wherein the water soluble organic polymer used are sues—as soaium carboxymethyl cellulose, methyl cellulose, polyvinyl alcoho~of oommzr~iat grade.

A process of making vitreous coating composition suitable for yellow variety brass substrate substantially as herein described with reference to the examples.





Documents:

260-del-2000-abstract.pdf

260-del-2000-claims.pdf

260-del-2000-correspondence-others.pdf

260-del-2000-correspondence-po.pdf

260-del-2000-description (compelete).pdf

260-del-2000-form-1.pdf

260-del-2000-form-19.pdf

260-del-2000-form-2.pdf


Patent Number 213225
Indian Patent Application Number 260/DEL/2000
PG Journal Number 01/2008
Publication Date 04-Jan-2008
Grant Date 24-Dec-2007
Date of Filing 16-Mar-2000
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI -110 001 INDIA
Inventors:
# Inventor's Name Inventor's Address
1 SUNIRMAL JANA CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE CALCUTTA 700 032,INDIA.
2 AMITAVA MAJUMDAR CERAMIC RESEARCH INSTITUTE CALCUTTA 700 032,INDIA
PCT International Classification Number C23D 5/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA